I can help a bit ...
1. We've booked the upper/lowers and always get upgraded to a regular inside. But what I've seen, they usually have a sign saying the ship is sold out otherwise. Carnival's inside cabins are fantastic size (especially when they beds are separated). We did move them so that they were like an "L" shape, which gave us tons of floor space. Also, you get a nice toiletrie basket on Carnival.
2. Don't recall a wine package on Carnival.
3. Soda card is $29 (I think!)
4. Food has been getting really high marks lately with Carnival ... I would say it was better than what we've got on Princess two times.
5. Sorry never been to Dominican.