Hello anyone,
First timer here with a couple of questions. i am currently working on a bathroom remodel. i have taken out the tub and all walls and i am on a concrete slab. i am installing hardibacker on the new shower area. i had a composite shower pan poured. the pan was poured into a thin fiberglass form that has sides about 2" high. the pan was installed and i put the hardibacker down to the shower pan (1/2" from the pan). I now have several questions.

1. how should i build the curb? mud or with hardibacker will the mud be ok on the compsite pan?

2. should i have put one of the plastic/rubber liners in before the composite pan was installed ( the shower pan dude said no)

3. how far down should i put the screws in to the hardibacker

*i did install a plastic liner between the studs and the hardibacker.
thanks for your time!
-dirt diggler