Beer is about $4.50 - $5.50 a bottle. Sometimes they do a 6-for-5 offer. Spritis are around $7. Given the exchange rate I think it is cheap. Here is a link to their cocktail prices http://travel.webshots.com/album/559018541CiiBCu?vhost=travel.
Does any of the ships cater for whelchair bound clients?
All RCI ships have accessible staterooms. They are renouned for the care and facilities they provide.