The Force in SE4

[Slick]

There could be some expensive facilities also giving various system bonuses and/or research/intel; possibly include also happiness or medical areas. I'd look into using some of the Psychic techs being restricted to Jedi/Dark Jedi.

Definitely make Force-related things cost prohibitive to accumulate in large numbers. To be true to the genre and to balance the game, these can't be what will decide the game. They should be used for the most important offensive/defensive plans and should be able to be overrun with sufficient numbers of conventional means.

I'd also make Jedi fighters very fast, just for the coolness effect.