All good posts, but not getting into the nuts and bolts of how it works...
You control EVERYTHING in your Empire(s). (REALLY a pain in the ass when you control more than one Empire, you need a player for each!)
You control diplomatic relations with planets in your empire, and with other Empires. You set which starships are going to be built, which variants of which starships are going to be built, etc. How many ships get the "+" upgrade this year, EVERYTHING.
Ship combat can be resolved strategically, by a die-roll ( An F-CA almost always beats a K-D6, etc) OR you can resolve individual combats with SFB. WARNING:::: THIS option will make individual turns take WEEKS/MONTHS and games take YEARS!!!!
Which really kicks ass, but makes for a bitch when Thanksgiving comes and you need the big table!
Have a nice day!