The suite concierge can make your reservations for the suite guests (if you are staying in a full suite) in advance as they will reach out to you the week before.
As long as you are willing to move to another ship and sail date there really isn't any difference between the old policy and this new one. You will pay the $100pp change fee just as you would have in the past.
Having sailed on Oasis at Christmas with the UDP you will be able to choose from Izumi, Hibachi, Portside BBQ, Playmakers or Johnny Rockets. Make sure that if you want Izumi or Hibach you book that as soon as you board.
If you bookedbinder North American terms you can change a guest up until 72 hours prior to sailing as long as one guest from the original reservation remains.
You won't get anywhere with trying to get the extra refunded. I have had success in getting cabins changed again after Royals move so that my clients staterooms were close together as they originally booked.
Just my opinion but they should have either held off rushing to get all the ships back to service or sailing at close to full capacity so they could have the ships properly staffed so they wouldn't have to be cutting service.