If you have a concrete block wall which you want to use as a shower wall, then don't mess around with building it out with a studded wall.
If it works at my local ymca, it will work for you.
Just waterproof the concrete block with some hydroban, aquaban, redguard, whatever you can get your hands on. Then tile the wall.
Some will tell you that you will have a lot of lippage in that wall. If your mason had any skill at all, that wall will be fine. If they had known that you would put a shower in that area, they would have just cut the joints instead of striking them. Won't matter now, you will thinset that wall and backburn your tiles or vice versa and if you think you will have a lippage problem, you can go with smaller tile. A 6" tile looks nice on a wall, and another way to reduce lippage is to use a random pattern. So don't stack the tile straight up, rather use a 1/2 bond or random bond.
In my neighborhood, where the homes were built in the '70's with concrete block basements, a shower was built in the basement when the basement was built. The shower walls were 4" concrete block and acted as a stabilizer against the outside walls coming in.
There was a simple floor drain underneath, and the plumbing to the mixer was exposed on the wall. This shower was not used everyday.
I don't know what type of luxury shower your are looking for, but you could take this basic design and just put some epoxy paint on the walls as well. You could even leave the plumbing supply exposed.
As far as your angled wall, that is a bit of a challenge. You could run the plumbing up the corner, then frame a wood wall in the 45 degree area. Set it up off the floor on a course of brick or block. Attach it to the intersecting walls by screwing a 2x4 to the intersecting walls, and attach the 45 degree wall to this, then put tilebacker on top, tape.
Feel free to beat this plan around a bit and hopefully we can come up with a plan that will work for you.