Micro Repair Bots will certainly help, as will moving damaged ships into planetary orbit. And, IIRC, you can put points into repair capabilities when you set up your civ at the start of the game.

As to coded repair rates, maybe the more informed here can answer that....I don't know the answer.

The whole alliance thing is broken, IMHO. For example: Civ A is allied to Civ B and to Civ C; Civ B declares war on Civ C but Civ A doesn't have to take sides...can remain out of the conflict, and still be allied to both. That isn't how things work in the realm of diplomacy. Civ A should either have to take one side or the other, or break both alliances and become neutral with both.

As to attacking starbases, bear in mind what form the starbase attack takes. Any weapon it's equipped with that your fleet has defenses for (eg. beam attk. vs. shield def.) can be deflected if your defense is high enough. But...if the attack is missile or gun (using the above example) you have no counter and will suffer higher damage. The reverse holds true as well (what you are attacking with vs. what the starbase defenses are). The same principal holds true for fleet vs. fleet.

Refer to this link for info on all starbase modules:

galciv.wikia.com/wiki/Starbase_module

There are no modules that add those values to the defenses of starbases.

There are only two sorts of modules (not counting racial-specific ones) that increase the defenses of the starbase. Invulnerability Bloom, Electro-Magnetic Surge, and Overlord Armor from near the end of the defense tech tree, and the modules from the Starbase Fortifications line. Battle Stations Two to Four are supposed to increase the defenses too, but that doesn't work, because a module can have only one type of ability.

The Starbase Fortifications modules are the only ones that make sense in the scenario of the OP. That would be three modules (six, if you also count the attack modules), each increases the defense (or damage) in one category by five. Depending on which of the modules are used in case of the OP's starbase, the damage and defense values could be anywhere between 1/1/1, 5/0/0 and 6/6/6, 5/5/5. In the best case scenario, it is tough, but doable. While in the worst case scenario, I'd be surprised if you did any damage at all.

As Regentofsparta said, combat is turn-based. The attacker shoots firsts, then the defender strikes back, including all destroyed ships (unless the attacker is a Super Warrior, but that counts only for the first round).
The actual combat-mechanics are little bit more complicated. The values for damage and defense are rolled between zero and the max value. For weapons, the max value is pretty straight forward. Just take a look at what the ship-stats say.
For defenses, it depends on if they are on-type or off-type. If they are on-type (e.g., armor against mass drivers), then it is just as the stats say. If they are off-type (e.g., shields against mass drivers), then the square root of the regular max value gets used (I think it then gets rounded up, but am not sure). After that, it gets even more complicated, because the max value for defenses gets reduced, the more damage is dealt.
For example, let's take three of the OP's ships against another one with the same values. Ship Nr. 1 rolls a one in damage, while the enemy ship rolls a two for defense. The enemy ship doesn't take any damage, but the max value for defense gets reduced by one, and is now at one. Ship Nr. 2 rolls a two for damage, while the enemy ship rolls a zero for defense. The enemy ship has now lost two HP, and the defense strength has been reduced to zero. Ship Nr. 3 rolls a one for damage, and automatically applies them to the enemy ships, because it has no defenses anymore. Now, the enemy ships rolls a two for damage, while Ship Nr. 1 rolls a one for defense. Ship Nr. 1 looses one HP, and the max value for defense gets reduced by two points. After that, the second turn of combat begins, and the defenses for all ships are back at full strength.
In case of a stalemate (all ships from both sides got destroyed), there are two possible outcomes. If one side has a ship with a bigger size than the other one, then that side wins, with this ship surviving (but with only one HP remaining). However, if neither side has a bigger ship, then the attacker wins, with the most advanced ship surviving (also with only one HP). I'm not exactly sure what "most advanced" means in that case. Either highest tech or highest level, I guess.
There also are two more things to consider. For one, having multiple weapons on board is very useful. For example, if you have six weapons on board, you could, in theory, destroy up to six enemy ships, as long as each weapon deals enough damage. The other thing is Luck. The Luck ability determines the minimum value for your damage and defense rolls. For example, if you have a Luck ability of 25%, you use 25% of the max value of your weapons and defenses as minimum, instead of zero. That is pretty much the only known bonus Luck provides, as far as I know.

I'm not an expert regarding combat, so I probably forgot something, or mixed something up, but I hope that was useful to you.

The amount and strength of the weapons onboard your ships, and how much damage is needed to destroy the enemy ships.
For example, if an enemy ship is badly damaged, and your first ship can destroy it with only a shot from one of it's weapons, it will then be able to use it's other two weapons to attack the next target. Your second ship will then have an easier time to destroy that one, allowing it to use most of it's weapons to attack yet another enemy vessel, and so on.

60%, if you also play as the Drath, and have Xeno Mysticism researched, and 70%, if you play as the Altarians, and have Xeno Mysticism and Divergent Evolution researched.

Great, thanks to all of you for your replies!

Regarding the values of defense and attack for the starbase I mentioned, I should have also mentioned that I´m using the APT mod in its "fix only" version. I think it doesn´t change any value for modules, but I may be mistaken. Regardless, I understand now that bigger fleets are needed, and even better if they have more than one weapon type.

I´m actually now in my second game, again as the Terrans but in a bigger galaxy and with a higher difficulty (went from Normal to Tough). Gotta say, the difference in AI competitiveness is remarkable with the higher difficulty. In Normal I had no trouble at all in remaining the most powerful and advanced civ, but now I´m severely outclassed by the Torians, the Thalans and the Drengin, and at the same level with the rest. I also had very bad luck regarding planets, with only a couple class 5 habitable planets near my starting position. Buy, hey, that makes it more interesting, doesn´t it?

Thanks again for your help!

Yes, you keep buildings for which you have the technology to build them yourself.

And yes, uphill struggles are so much more glorious than games where you're in the lead from the get-go.

Once you have mustered an invasion fleet, you might use a spy to examine all your potential targets during your approach.  The you can prioritize which to invade first, etc.  For example, if you spot that one planet has a civ-wide soldier bonus facility (TirQuan Training, or something), then take that one first!  Also, any planets with things like Eco Capital or logistics or miniaturization buildings should be among the top targets.  Capturing them not only boosts your empire, but also weakens the enemy greatly.

If the AI has a counterespionage building on a planet, you cannot use the spy but you can still "see" the planet if you have taken the time to gain a high intel level on the AI empire.

One other thing, an AIs military rating may be overstated if they have built a Spin Control facility and have warships in orbit there.

Sounds like it won't be long until you're ready to go up another level in difficulty. You just need to get a bit better at the colony rush (although sometimes there is no compensating for a crappy starting position, that's when games really get interesting ). The Thalan invasion mistake is one you'll most likely never make again, which will significantly increase your gains next time. Also, try not to kill every ship your enemy has, but only those that "annoy" you (the ones that directly hinder short-term goals, say invasions in the next three turns, or "spare" ships in orbit around hostile planets that could sally forth and blow up an innocent transport of yours). As long as your enemy has a decent fleet, he'll think he might stand a chance and is less likely to surrender to someone else (or you), allowing you more time to take those juicy planets he might otherwise give away to someone else. As for invasion strategy: it can help to hit strategic planets as described above, but don't lose yourself in quests like these: it can cost you quite a bit to escort transports deep into enemy territory. I usually conquer myself a nice corridor into the enemy heartland instead (every planet that takes too long to build a warship instead builds the cheapest transport I could design), which focusses the fighting and the invading and makes it easier for me to keep my transports alive and my freshly acquired planets safe.

Medium hulls are, as you already noted, quite powerful and are worth getting early!

Korx and then go Neutral. Still a terran-like experience, but without the weird diplo-bonus and an excuse to go all evil on your ethical choices until you research Xeno Ethics. Their trade allows you to befriend civilizations relatively early (or they'll hate you for being evil), but must somehow be balanced with a good colonization rush ánd getting XenoEthics relatively soon...

If you want to really change the way you need to play: go Yor or Thalan.

Ok, thanks for the suggestions!

Ninja Racing Games

Click on the Planet/Ship List button (or press the F1 key). This will bring up a list with all the planets and ships in the game. Search for the planet you're looking for (you can sort the list by Name), and then click on the planet icon. This will move the camera directly to the location of the planet.