Circuits are EXCELLENT, and use inspiration from real tracks in certain places...
There's no Formula Ford in LFS, but I'm not sure what you mean by "how do you race". It involved lots of cars driving around trying to win.
Lots of people like lots of different cars and tracks - there are 744 possible combinations. Road cars, Race cars, Formula cars, FWD, RWD, AWD, Front Engine, Mid Engined (no rear engined as far as I can remember).
Basically, if you like the demo, and have a few quid on you, get it - you WON'T regret it.