I can answer a couple of the questions. The adult soft drink package is $6 per day, plus 15% gratuity. So it would be $75.90 for your 11-night cruise. Two formal nights on an 11-night cruise, seven casual nights, and two "smart casual" which really means casual. RCI has theme nights but my experience is they don't make a big deal out of it. It really depends on the itinerary. For instance, we didn't have them on our Alaskan cruise this past June but I have seen tropical and country-western nights on Caribbean cruises.
Sushi is available at the Jade buffet which is part of the larger Windjammer buffet restaurant. It isn't a sushi bar though. The Monarch Of The Seas is the only RCI ship with a dedicated sushi bar.
Looking at your itinerary, I'd expect the formal nights to be on your first full day at sea (October 16) and then on the evening you depart Lanzarote (October 21). I don't know for sure but these are quite likely.