Doesn't give much, civilian vehicles give something like 100$ but armed vehicles and tanks give up to 6000. #2 An area where you can sell the vehicle you drive in to it.
#1 An area where you can park and set yourself as an owner of any vehicle for a fee, the added bonus is that the vehicle saves (due to the scripts sets an owner and the save script saves all vehicles that has an owner) I asked around and i have two popular mechanics on my server but they are very poorly implemented(my fault as always).