All the touchscreens I've seen are glass. They overlay the screen and the film is adhered to the glass.
I always hook mine up before reinstalling it and check for what is up or down. It's possible that the calibration program takes care of figuring out up or down but I never felt the desire to find out the hard way.
If it is too thick, the housing will constantly simulate a touch at some point along the edge of the screen. You'll have to find a way to take the pressure off.