Wife and I were just on Mera for 2 nights in YC interior.
Cabin is small compared to the balcony cabins, bathroom is particularly small, but doable. I’m 5’10”, 210 lbs and shower was adequate, tight but small. Not a lot of storage, pack as light as possible.
Since the lounge (deck 15 forward) was a short walk up stairs, I would go there while wife showered and dressed. The pool is on deck 19 forward, restaurant on deck 18 forward, there is not deck 17.
There was a buffet for breakfast and lunch on pool deck, not sure about supper.
Tipping - I usually tip extra even if not expected, add more if I required extra from the butler or room steward.
Thermal spa included with YC.
Unisex toilet on lounge floor, not sure about deck 18, but cabin is always close by in YC.
We are in YC interior again in October.
Hope this helps!