The answer to all those questions is "almost certainly not". This is because if you were allowed to do such things, it would open up avenues for scammers and other such opportunist money-for-ingame-credit websites..
If the items could only be gifted and not traded, the harm is minimal vs the benefits. There will always be avenues for abuse by ******s like RMT and scammers, but if you intend to let that be what drives your decisions, you might as well shut the game down and not bother.
Punishing the whole because of the potential abuse by a few is a bad way of doing things.