Yes you can get as many fast passes as guests in your room. The pass is your actual room key so you just need to get room keys for every member you want to have a fast pass.
You can get up to 5 passes for a 2 queen room
I think you only get 2 checking in, but they might be able to get you more due to family
I believe it's one Express pass per hotel key.
4 Express Lane passes? Good question. My wife and I each got one and we only had one room. I'd imagine all guests staying at the resort would get an Express Lane pass.
Thanks! Your answer is awaiting moderation.