Hi lakeside,ca. Welcome Aboard Cruise-Chat!
I only can give input on 2 of your questions.
The best area on a ship for a cabin is subjective to one's tastes and concerns. If one is concerned with motion sickness, lower mid-ship is best. The Verandah deck cabins have at least 3 different Categories, so that would be subjective. Would I pay more for the same cabin type to be on Verandah deck? No.
The cabins have metal doors.
I am sure you will get more answers, and again Welcome Aboard!