I certainly can not answer all your questions but I would arrive about 1pm; you should be able to board almost immediately. The chssee platter on the Sea last year was outstanding; the quality of Champagne will be a little better than bad; no, it will be probably similar to mayb Korbels. If you are a champagne lover you may want to upgrade. As for the butler, someone else will have to help you here, we have had concierge service many times but not the butler service.
As for what to do as soon as you board: this is different for everyone. We always go to our cabin, maybe unpack our carry on, but your butler will do that I am sure, if you want him to that is. Then we head for a quick bite to eat and start exploring the ship. As this is your first cruise you will want to be on deck when the ship starts to sail. Hope this helps some. NMNita