Like the pre-cruise planner, on board you may have discounts. If you know for sure you will buy it, buy it pre-cruise and if by rare chance it’s lower on board, cancel (you will get refundable OBC) and buy it on board.
At the bottom of the main page of the app there should be a link to browse ships - that should list all of the ships in the fleet (and all sailings
for about the next three months). She is moving to Cape Liberty this week, so the 5/16 sailing is the first one that will have useful info, though it may not be complete - it should be by Friday.
Boarding is different from check in - everyone can check in whenever as those times are not really enforced anymore at most ports. If everyone shows up after boarding has started (sometime after 10AM), you can board together. Everyone will be on board by lunch time.
Smoking is limited to the usual locations. You can view Spectrum related threads, which should have a review of something like you will encounter, via the drop-down menu on the main page here at RCI section of CC.
It's likely a temporary issue. You can try a different device/browser to see if you can duplicate the issue. The price w/grats included has been reported by others in a different thread.
It seems RCI is trying to confuse things by not making it obvious that they likely mean an E and D category GTY instead of the generic XB GTY. I would still be weary of picking any non-category specific GTY if you really want to stay away from E cabins. Not sure that even an RCI CSR call will eliminate that possibility.