1) Not that I know of. That doesn't mean much though=-)
2) Check out the
sci fi crossover mod thread.
3) No I don't think they can, unless you re-mod them as small ships. But then they can go through warp points, and they're not fighters any more, and you have problems with fighter components being available to capital ships. Oh, and your 100,000 fighters (or even 10,000 fighters) would violate the game's "maximum units in space" limit. And it would be a nightmare even in strategic combat. Plus, you do have to pay to build them, and you'll need carriers to move them, and the bottom line is that fighters just aren't as powerful as the equivalent tonnage / cost in ships. What I'm saying is that they don't seem to unbalance the game at all.
4) Drones are yet to be implemented, MM didn't have time before the game's first release. I think they are high on the priority list though. It seems the patches so far are concentrating on bug fixes and minor (ie easy to implement) new features, but once those are out of the way I have a feeling drones will be at the top of the list.