Basically, in a nut shell, and a rather smallish one. With regards to updates, you would just need 1.255F and you'll be ready to race. When you just download the trial you'll only have a car or two to try with a track or two (can't remember), once you've paid for and unlocked it, it makes a few series and tracks available, but thats not what you'll be after.
http://www.rfactorcentral.com/
^ Go there and have a look at the variety of cars you can drive, its alot easier than explaining it all, also there is a list of tracks there. However that only lists 'legal' mods, which havn't borrowed/stolen body shells etc. from an already existing game.
Well wheel wise, you'd be best off with a Logitech (In my opinion, mainly as they are the most reliable mainstream wheel producers)
http://www.overclockers.co.uk/productlist.php?groupid=702&catid=288&subid=353
The Formula Force EX is a good wheel for its price, just dont get it there, too expensive.