Tile contractor here. It please stop and start over, you will regret it if you don’t.

You have this set up for a traditional “water in water out” system. 3 piece clamping drain and rubber bladder. First you need to pre slope your pan. Meaning you need to use dry pack mortar to form a shower pan under your bladder first, than put in your shower bladder, souround the drains weep holes in pea gravel, than use again dry pack mortar to build your shower pan. Concrete had no place in a shower for a lot of reasons.

You could go the more modern and simplistic route with a topical membrane shower system. Please Google “wedi” or or “Schluter” shower systems.

Currently your asking for mold and water damage issues

There’s a saying in construction. There are two types of concrete, concrete that is cracked, and concrete that is going to crack. This is nothing

UM should go tight within reason to the drywall 1/4”-1:8” gap. You would never run UM vertically. What your seeing vertically is a fleece lined waterproofing membrane. The 2 most common products for this are made by Schluter Ditra (UM) and kerdi (waterproof membrane) in a basement there is absolutely no need to use the fabric membrane on the wall, it’s mostly used in showers and bathroom floors. Be sure to honor the control joints cut into your concrete slab. Otherwise they will in time translate to the tile above and crack them. TCNA section EJ 171

You need to remove the paint mechanically by means of a grinder. The self lever will need a primer after the concrete is clean and scarified. Look into uzin nc 150, or laticrete nxt. Read the instructions throughly. This is an expensive process to do correctly. It's cheaper to have a professional do this than it is to mess up on your own than call in the pro