I've been digging through all these posts, and hope I'm not asking silly questions. If they've been answered elsewhere, please point me in the right direction!

My husband I are pretty comfortable with most DIY, but are not experts on shower-building. Here's the deal:

We live in a mid-60's tri-level w/a half basement. Our master is on the ground floor (used to be a family room) with a bathroom that used to be a laundry room. Previous owner did some bizarre things in that bathroom and, long-story short...the bathroom is now concrete floor and stud walls. This bathroom is on the ground floor, and has no basement underneath, but the back wall of the shower (where the plumbing is) is a shared wall with the new laundry room in the basement.

So: the plumber is coming next week to put in the correct drain for a shower and will leave us with the adjustable drain and a level floor (right now there is an old floor drain for a washing machine with a big slope). After that, my brother in law who works with concrete is going to help us build the shower base. This will be a tile shower with glass enclosure and a curb.

Questions:

Since the shower base will be going on top of the concrete slab, is there still some kind of membrane required? Where *exactly* does it go? I've seen it over the mud base and under the mortar for the tile...is this the correct way? I don't want water escaping and running down my basement wall or somehow seeping into the concrete slab.

My brother in law can build the curb, he does this for a living, but not in showers. What material should he use to build the pan with the slope and the curb? He doesn't usually do showers and I'm afraid he might not be up to speed.

We will use some CBU for the shower walls then a membrane over that, right? I've seen mongoct's long thread on Kerdi, which was very helpful, but my brain's swimming from information overload right now.