Yeah you're good to go then.

not necessarily , they drill the holes before tempering the glass .

are the edges polished pat?

I've never seen a factory drilled tank that was drilled on the back let alone tempered on the back

But that being said there are always exceptions

I'd say 80% chance it wouldn't be tempered

That being said your statement is correct in lots of cases, like by rr 72 bowfront

Factory drilled bottom with tempered bottom which I find to be real common on bowfronts

Not sure what you mean by polished. I thought all tanks were polished. It's not a custom tank or anything.

Is it common to have tempered glass all around? I thought it was usually just the bottom.

no not all tanks have polished edges. i doubt they would temper your tank and if they did it would be probably on the bottom panel only.

i also doubt they would temper all panels , cost is too high unless it was to use a smaller thickness in glass.

what company made your tank?