by hinotori
1) For expansions, personally, I would get Shattered Empires. Avoid the Imperial Strategy Card, and you avoid all the unhappiness expressed in the various TI3 forums about the ISC I card. YMMV. Instead, Use the Age of Empire variant, which uses the ISC II card that is in SE expansion. In the meanwhile, make your own ISC II card from the image on page 17 of the SE rulebook.2) As for player resources, BGG user Psymin has put together a package of his favorite player aids. Make a copy/booklet for each player.
3) As for player races, I don't believe any one race in the base game is harder to play than the others. I find that discovering and leveraging the asymmetrical abilities of each race is one of the joys of playing TI3.
Have fun!