1) You’re right that you wouldn’t get any reciprocal perks.
2) Drinks are all day and include soft drinks, cocktails, plain & sparkling water and speciality coffees. There is a range of cocktails (and mocktails) on the included list, but you can ask them to make any cocktail with the included spirits.
3) The showers are OK. They are on the small side but my husband is 6ft and not slim and manages fine. The shower curtains don’t stick to you as they’ve been replaced with heavy curtains
4) Verandah plus are ordinary Verandah cabins but with some extra perks such as a bottle of spirits in your room, a couple of meals in the speciality restaurant, a free bag of laundry per cruise week.
5) we’ve never had a problem with the stability - but if you think you might have a problem go for midships and low down.