2. Survey ship set on autoexplore may enter wormhole and get teleported to the other end of the galaxy. Even though the range is exceeded, it can still autoexplore (but you cannot manually move the ship).
This has been in the game as long as I can remember. Honestly don't recall ever trying to give it a new move order, but can you imagine how inconvenient it would be to be teleported halfway across the galaxy and be unable to explore anomalies until you got back in range? I'd say this is the lesser of the two evils, especially since it tries to get back to your space, but just so happens to be exploring on the way.
3. Arnor dreadnought attacking Dreadlord ship may occassionally get a massive HP repair after winning a battle.
HP is repaired when a ship levels up, IIRC. Or maybe it was just the new level's hp is added to current hp. I forget, it's been a while.
4. A single powerful ship attacking a Dreadlord ship usually wins the battle. But when this ship is combined with an identical ship into a fleet, attacking the same Dreadlord ship results in a win but at a loss of one of these ships. Is this a bug or a result of Dreadlord Courage ability?
This is a result of "destroyed" ships firing back in DA and TA. The "single powerful" ship could withstand it, but for some reason it's not the priority target (attack / defense + hp).