Insulation, Radiant and Vapor Barriers - Vapor Barrier For Radiant Concrete Floors?

I'm building a new house with 2" concrete floors throughout. I will have pex tubing run through this concrete for a radiant heat system and placed onto the sub flooring.

My questions:

1. What kind of vapor barrier should I use to protect the sub flooring while the concrete cures?

2. How should the pex tubing be attached to the sub floor?

3. Will there be any issues if the vapor barrier is punctured by attaching the tubing?

So you already have a 4in floor poured?

No I don't have anything poured as of yet other than the slab on grade - ground floor. I have the pex tubing installed in that floor.

When the framing is complete, I will have two more stories equalling about 2500 sqft. where I will have 2" thick concrete floors poured. This will be poured on top of plywood sub flooring and the concrete will be dyed and used as a finished floor.

Before the concrete is poured I would like have my pex tubing in place and then have the concrete poured on top of it.