- Are there any different races? (I can't chose one - or will there be?)
In v0.3.14, no. In the soon-to-be-released v0.3.15 (you can get an alpha from sourceforge for Win32), yes.
- Is there a "combat-mode" where you can control units while the battle is going on?
The 3D combat system is incomplete and not yet usable for actual gameplay, but is being worked on.
When I played Moo2 and Moo3 which features from those games are integrated/copied and which one will i be missing?
What is the main difference of this game compared to Moo2? What do you guys want to change/improve?
The main difference now is that FreeOrion is incomplete and imbalanced. Although some people seem to find FreeOrion fun, it's not yet intended to be a fun, playable game, which (arguably) MOO2 and MOO3 are.