What about the dust from the pilot holes?

I'm...
- Installing plywood subfloor over a concrete slab with Tapcon screws.
- Drilling pilot holes down through plywood/vapor barrier/concrete.
- Seeing that the drilling pulls up dust from the holes- the dust ends up between the concrete and the vapor barrier above. 20 screws per 8x4 sheet - that's a lot of dust.
- not seeing a way to effectively vacuum out the dust from this space.

Is leaving the dust there - between the concrete and the vapor barrier - okay?

Will that dust create a "crunching" noise from footsteps above?

I would think it a big deal, but every guide for "installing a floor over concrete" guide strongly emphasizes sweeping and vacuuming the concrete slab first. So either dust is a big deal, or... it isn't?

I do not see any loss of strength in fastening over the fine dust from drilling pilot holes. When you carefully tighten the fasteners the dust will be compressed into the face of the plywood so there will not be a bump that would be noticeable. Sweep the surface before you start with the flooring installation.