Invent trade, culture, ice and volcanic colonization and forget about civilian tree for a longer while.

I just picked this game up a few days ago. I've played through 1.5 games. The first time I lost pretty handily. I'm moving along nicely on the second game.

Regarding the Hanger defense:
1. How many should I build around each planet?

2. Which is better for defense? Bombers or Fighters? How is this determined?

Thanks!

My only real suggestions are: Race to the trade port tech, improve resource gather rates, and ALWAYS FOCUS ON CHOKE POINTS!!! If you focus on fortifying bottlenecks and save resources for a balanced fleet, the AI usually can't hold you back. As far as military techs go, I personally improve shielding and hull strength as they apply to nearly every unit. I only improve weapons once I'm confident I've properly improved the survivability of my investments.

You can't field much of a fleet without a strong economy. Then again, you can't build a strong economy without 'convincing' planets to join your cause. You get a lot more mileage from adding planets than researching economics though, except trade ports and colonize all planets abilities.

Multiplayer and single player are very different. The AI will not: cruise around your choke points to 'inner worlds', build much of an economy, build varied fleets, build much in the way of planetary defenses, use choke points, and a few other things. So, I'd preface questions always with "vs. AI" or "multiplayer", and expect wildly different answers to each.

A lot of the fun in this kind of game is finding the balance you're asking about. Should you try to take on the nearby asteroid with only your starting capital ship? Try it. If you get the answers from the forums you'll have missed a good bit of the fun, at least vs. the AI.

I also disagree with the 1:3-4 fighter to bomber ratio.

Fighters excel at hitting light (LRMs, Scout frigates, Seige Frigates, Bombers) armored targets and can be used defensively to take out enemy strike craft.

Bombers are better at hitting medium, capital, heavy, and (especially) very heavy armored craft (heavy assault cruisers, tactical structures)

In SP, some of your biggest threats are seige frigates (pirate and AI player.) In MP, additional major threats are LRM spam (which can hit SD platforms from beyond their range) and carrier strikes (where fighters are useful defensively against the strike craft).

That's why the more common (and IMHO better) advice is a roughly 2:1 ratio of fighters to bombers, but where you expect to hit enemy capital ships in the grav well, increase the bombers.

When you're defending the system, you can manually vector all your fighters onto the seige frigates or LRMs. Essentially, a primary purpose of static defenses is to delay the attacker while you jump in your defensive fleet, and the ability to take out the seige frigates (the only thing besides a capital ship that can, in the early game, take out your colony) is hugely helpful, and the ability to kill passing scouts is just a bonus.