I don't know an answer for your second question, you'll have to ask someone else about that, but I can help you out with number one. Winter is common, therefore you can't trade it. Water and Light are base dragons, and they can't be bred so that's why they can't be traded. Magic, Virtue, and Night can be traded even though they're base dragons because they are only available through breeding or being bought with gold. Metal is also a base dragon, but for the Metal section. Even though it's a breed able/buy for gold dragon, it's the base dragon therefore it cannot be traded. I hope u can understand what I'm trying to say