@rangerr 40 minutes is a bit tight (especially during the holidays), but should probably be ok if everything is running smoothly. The real problem with such a short layover is that if your first flight gets delayed even a little bit, you and/or your bag may not make the next connection and might have to wait for the next flight. If you’re traveling earlier in the day, than there are probably several later flights going to your final destination, but if it’s in the evening, you might get stuck in a hotel.
I don’t want to scare you away, (because as @nikipedia has pointed out, your trip really will be fucking awesome), but I would hate for you to not be mentally prepared for this possibility and then have a panic attack or something.
If the Mandalorian armor is a one-of-a-kind thing, I think @WestRiverrat‘s advice of shipping it Fed-Ex/UPS is a good idea. If it’s replaceable, than be sure to make sure the airline’s insurance for lost items covers the price of replacing it. @bobbinhood is correct in that the vast majority of the time when a bag misses a connection it’s on the very next flight, and will be delivered at the airline’s expense to you boyfriend’s house. You should definitely put your contact information inside the bag as well as the tags on the exterior just incase the tags come off during travel and they need to open it up to find out who the owner is. I just think it’s wise to plan for the worst case scenario, even though there’s a very slim chance of it ever happening. It gives me confidence and reduces my stress/anxiety because I know that no matter what, I’m going to be ok. Planning and preparation can go a very long way to making you feel better.
As for the gift for your hostess, things you’ve made will always go over well. If you’re artistic then something small that you’ve spent some time on can quickly become a treasure to someone. You might want to avoid bringing in foods because it could cause issues going through customs.