Hello!
I'm happy to answer any and all tile questions and provide a pictorial documentary if needed
1. Moisture resident drywall is mandatory.
2. Do not set the tile over the sheet rock, so joint tape is optional.
3.Acrylic modified thinset mortar. Mastic is not a good choice in a wet area.
( yes, it will last for 12-15 years, but why not go for the Lifetime Install™? )
Would you like to see an example of a recent bathroom remodel?
KT