lots of info on Reef Central about useing a Roto Zip cramic cutter for glas

If you get the proper tool to score the glass, and are careful (might take a little practice too) then score and crack should work great, this is how window companies cut glass, with a machine that scores and breaks it.

The "best" way to drill is with a diamond drill bit on a stationary drill. This is how I have drilled my sumps, the bit is expensive but pays for itself in the end, and it is just cool to drill your own glass. It is definately possible with a rotary tool though, I read the same post on RC.

You can get the bit's cheap on ebay. They come out of hong kong and work well.

Which bits, rotary tool cutting bits, or diamond drill bits?

This is a supplier in Hong Kong that lots of people use

http://www.richontools.com/catalog/c8_p1.html

I think I am going to cry, I soooo overpaid for my 2.5" diamond coated bit!