Advice for tank returns.

I would go up and over for sure. One could argue that drilling a secondary drain may be a good idea.

 

you don't have to flip it on it's side to drill it out. I have drilled tanks while sitting it place. With a second person spraying a steady stream of water at the drill bit/glass it can be done.

 

Yep. Andy is correct that's how I drilled the holes for the closed loop on my big aggressive tank. also the thicker the glass the easier it is to drill it takes longer but the chances for it to break are less. the hardest tank I ever drilled was a 10gal.

 

Depends on your return pump. I would do a beananimal style overflow if possible. I had one on a tank and it was close to silent. It requires 3 holes to be failsafe.

 

I have one these if you want to borrow it:

http://www.bulkreefsupply.com/drill...rills.html