1. Resort Hotel >>> Link a Reservation in MDE. Yes, you use the confirmation number. It can take a while to migrate to Disney's systems. If it errors out after trying for a few weeks, call Disney. (There's a Disney internet helpdesk # that can help with this, but I don't have it handy.)
In addition to just simply not being in Disney's system yet, one reason the link could error is the total # of guests don't match, so make sure it is the same on both Marriott & MDE
2. Not sure, but I would imagine that's all available on arrival day. It is for the Disney hotels, AFAIK.