If both cruise lines, tell you to check in at the port, then you will probably need to check in at the port. I would not trust them to move your luggage between ships.
If feels heavy drinkers are at the martini bar, it’s likely that they are people with beverage packages not people drinking from the happy hour menu because the Martini Bar is usually excluded from the HappyHour. Capping the Elites at four won’t have any effect on those heavy drinkers at that particular venue.
Unless you are the seller of the mattress, the tag doesn’t apply to you, so don’t worry, “they” aren’t trying to tell you what to do.
and since you don’t live in Canada, you might not know what is illegal to do there.