Nice looking design, Robbie. I'd suggest Classic Traveller as a rule system. It's pretty straight forward and gives you a universe with all of the ingredients you set out. You can buy a CD Rom of all the classic traveller stuff for about US$30 and there is a hell of a lot in there - I believe in excess of 800 pages of printed material. To play Traveller, you only need to read the first 5 or so booklets.

Traveller comes in it's own universe, but it will easily adapt to a home brew universe as well.