My contractors recently ripped out my shower surround and put in
natural stone tile. They used a wet area barrier (like a vapour
barrier, but designed for showers) over the 2x4's and insulation, and
put wet area cement board on top of that.

You shouldn't have regular dry wall under the shower walls, though.
There is special "wet area" cement board for these applications.

Also, you should have some sort of pan underneath. My contractors put
in a copper shower pan, and then poured concrete in it and created a
drainage pitch. So if there is a crack in the concrete, there is a
copper pan to prevent leakage.

It was expensive to do all of this, but most of the times you get what
you pay for. If you are paying for labor, my advice is to not skimp on
materials, otherwise you will need to redo it in a few years...

Oh, and if you are considering glass shower doors, I wouldn't recommend
Holcam. Try finding a local glass maker that can do tempered glass. Or
better yet, stick with a shower curtain.