> Does the glass ever pull up when you cut out the hatch? Are there tips you
> can give to reduce this possibilty?

I have not had a problem with this. In my jigsaw I use a blade that cuts on the up-stroke so the base of the saw holds down the glass. A small amount of pull-away is not a big deal if you seal the edges as George suggested. The epoxy will wick into some pretty small seams. I then seal the edges with some epoxy thickened with Cab-O-Sil.