Question about tiling the bathroom now -

[Hassin Bin Sober]

4. It shouldn't be a problem as long as the tiles are adhered properly...

...and the substrate is attached to the walls properly.

Don't use drywall or green-board for a substrate in this case as the nails might pop or, in the worst case, pull through if there is any movement. You should never use drywall/green-board anyway unless you are using one of the latest state-of-the-art surface applied sheet membranes like Kerdi membrane or Noble products etc. In this case I would definitely stick to cement board.

I prefer HardiBacker cement 1/2 inch for shower walls attached with their 1 5/8" inch backer-board screws. Home Depot carries that product.

I prefer a surface applied (painted/rolled on) vapor/moisture barrier on the backer board (Redgard at Homer's) versus plastic sheeting behind the walls. This keeps all the moisture INSIDE the shower versus permeating through the tile/wall and condensing on the plastic to drain back in the tub. This also makes tiling easier as the cement board is sealed so it won't suck your thinset dry too fast.

I would use a GOOD QUALITY latex fortified hand mixed thinset (versus a mastic or premixed). The latex additive will give you the extra bond and protection against movement. Latex fortified thinset is a must-use for any glass tile anyway. I prefer Mapei Ultra-Flex 3 (Menard's) for all my projects. It's a bit pricey at $37 bucks for a 50 pound bag versus , say, $18ish bucks for the stuff Homer's sells.