1) Yes. You can rename more or less EVERYTHING - ships, planets, races...
2) Nope, the tech tree is the same for all races.
3) You can customize nearly every aspect of the game; some basic stuff you can change via menus during the setup of the game, more advanced changes can be done via editing .xml-files - techtree, race-setup, random events etc. - it's all .xml and thus easy to mod.
However, when changing stuff beyond what you can select ingame, you won't be able to play Metaverse, because, obviously, it would be easy to cheat. I don't know how it is with race alignments, but I guess that won't be a problem - in GC1 you could select each races alignment during the setup of a game and even randomize it, which was my favourite way of playing. Guess it will be the same here.
