I am rehabbing a condo my wife and I have purchased and I am finally done with the demolition and up to the building/remodeling part.

So, after having removed the tub and taking the walls down to the base hollow brick substrate (see photos)


I am trying to decide on the best course of action for covering the walls and creating the floor. Here are the options I am considering:
1. Attaching 2"x2"s to the floor and ceiling (with Tapcon screws as both are concrete) and attaching 2"x3" studs (turned so the depth is 2") to minimize the size loss and to square the room (walls are WAY out of square). Floor would be a mortar bed pre-slope, rubber liner and then slope bed. Walls covered in cement board (with plastic vapor barrier) and the whole room tiled.
2. Attaching 2"x2"s to the floor and ceiling (with Tapcon screws as both are concrete) and attaching 2"x3" studs (turned so the depth is 2"). Mortar bed to the drain, cover the walls in cement board (no barrier), then seal the whole area with a liquid rubber material (leaning toward Laticrete as it has the corner membrane material) and finish with the tile.
3. Attaching 2"x2"s to the floor and ceiling (with Tapcon screws as both are concrete) and attaching 2"x3" studs (turned so the depth is 2"). Floor covered with custom made floor pan, walls covered with cement board (vapor barrier) and the space tiled.
I have done a small tile floor and a tile back splash before, so I am not completely green with that part, but have no experience with creating the floor for proper drainage and waterproofing (as this is a condo, I am very concerned with water leakage and other tenants).
Would one of these three choices be better suited for a first timer? I know the custom pan will be over $1000 (unless I can find another manufacturer who can do it cheaper). I am leaning toward the one layer slope floor and the liquid membrane. Any input (pro and con) for each of the options is greatly appreciated.
Thanks,
Nick