If your contract has a cancellation clause, they will let you discontinue service, but they will also take the phone back, so make sure you sign out of everything and factory reset it. If you bought the phone from Samsung, and are financing it through them, I don't know about their financing contracts, but you will still be able to cancel your phone sevice. If you financed through the carrier, you may be able to negotiate a) a lower level plan and b) a longer payment plan for the phone at a lower payment.
Depends on if your in a 24 or 36 promotion agreement for example if that's the case you will most likely be charged what's owed or the full price depending on the situation and could goto a collection agency
