You should be able to make reservations on line. However, it may be better to wait until you are on the ship. If you try to book a restruant with one set price, the system will want to charge you.
Here lately I have not been able to book anything on line. I put something in 'mycart' and when I go to check out, it's all gone. 🙁
The ship tour, it's pretty good. We've been in the kitchen's, back stage in the theater and some other crew areas. Not all ships do the same "exact" tour.