Hello first time cruiser. In answer to your questions , it really all depends on what you want. I usually have an inside cabin due to my finances. I would rather go on more cruises than pay lots extra for a balcony. Insides are the same size as balcony cabins, minus the balcony!! If you can manage without seeing natural daylight then it's fine. Some people dont like that, it really is down to the individual. Personally I really like Britannia and dont really mind which deck my cabin is on. Some people prefer to be positioned mid ship as you're less likely to feel any swell but that's highly unlikely in the Caribbean. Hope this helps but at the end of the day it's down to your personal preferences.