I have a couple of more questions now:
1) I bumped into an alien race one jump from Sol. They have a planet there, and that's how I found them. I don't know if they've seen me yet. Ideally, I'd like peaceful relations, but I don't know anything about them, or even if they know about me. I've already put a diplomatic team to work, but I haven't contacted them yet. I read in another thread that I should turn on the transponder on the ship that found them, to alert them to my presence. However, I don't know how to do that, and I'm not sure it's a good idea. Any advice would be welcome.
2) I've decided to colonize Titan, considering all the minerals it has. the cost is somewhat high (about 8-9), but I have some terraformers to spare, and I'm not in a hurry. The moon has no hydrosphere, however, and I'd assume that one of those would be necessary to sustain human life. Does that matter in the game (apart from the fact that the albedo won't change), or can I go ahead an colonize it?
3) I'm still looking for advice regarding mining ships, although my immediate need for minerals isn't as high as it used to be. Basically, I'm interested in whether it's actually worth the bother to use them. Also, assuming that people think it is, how many modules should I put on a ship? Should I build one really big one, or several smaller ones?
Thanks again for all the tips and clarifications, it's helping me out a lot.