I would drop him off at the luggage drop off, since you go there first anyways. Tell the people directing traffic you have a rear ramp and they should be able to accomdate you.
The ship will be "dead heading" from Miami to Orlando. Not only will you need to pack up, then leave the ship, you will need to find your own way to Orlando.
These are holds placed on your method of payment to assure the money is there. At the end of the cruise, a one time charge will occur for the total. The holds will disappear after some time. If you used a debit card, this money will not be available until after the holds clear. This is why it is not recommended to use a debit card for your cruise.
Unfortunately, it sucks, but per the cruise contract they are allowed to change the ports. I've always said, if there is a destination you have your heart set on, book a land tour there.
Kosher for Passover is harder to do. Even a Kosher kitchen will need to properly cleaned in order to be able to provide Kosher for Passover food. So while the caterer can provide Kosher meals year round, they might not do Kosher for Passover.
With that said, my guess is those who are cruising over Passover on a non chartered group, are probably ok with what the ship will serve.
This is assuming the caterer that Royal uses can even provide Kosher for Passover meals.
Generally speaking, Kosher meals are basically frozen dinners. Unless they arrange to Kosher a galley and have it unavailable for the cruise to anyone else, and bring the appropriate food/dishes/etc on themselves. This can be very expensive.
Just to note, unless you are in need of an accessible cabin, please don't book it. There are plenty of people who can't cruise without it.
Now, if you book a guarantee and get it assigned to you, that's a different matter.