In theory no, in practice yes. This is done all the time. You want a certain car and they do not have it in stock. The call around and find the car you want at another dealer. They sell you the car and go get it from the other dealer.
Typically, no a felon cannot sell a car at a dealership in California. Unless, of course, they are the outright owner of the car in which they are trying to sell to the dealership, (and have all the paperwork to prove this true) OR they are under an employment agreement with the dealership, and it is their job to sell cars at the dealership.
no
yes because you don't have to pay for the car. But if the dealership does not want to buy it you can't sell it to them
Sell it.
no
Yes
Laws differ from state, to state.
yes
Yes, but you will not get much for it. You are better off selling it to Private Buyer, unless you are willing trade the car in for another, then selling to a dealer would probably be best.
Yes
as seller
Yes. It is called a trade in.