For the people putting a lot of hate, STOP IT! He has done his best making a very good game from an older one that is quite buggy, and a good job at that. (No, I am not talking about those who have been telling him of bugs and ways to make the game better, you guys are just as awesome.)
To take over the Cardassian Union easily, conquer Bajora(lower the strength to zero by destroying all the stations and ships). Afterwards, get your rep for the Cardassian systems at least 150 and beam do to the planets, and they become yours.
For Cardassians, start as a Gul. What you do is press TAB and look for the little boxes that appear outside of the Race Selectment screen. The box in the bottom right corner is Cardassian Gul. Shift-click that.
Thank you very much! I will indeed make more!