New UTH Installation questions

Got my new UTH and thermostat today. I have taken off the old UTH (great directions in the caging forum "sticky" http://ball-pythons.net/forums/showthread.php?66262-How-to-Remove-a-UTH!&highlight=remove+tank+heater) My questions:

Do you think it best to use the aluminum foil tape?
How do I get it to lay flat (no air bubbles) if I put the thermostat between the UTH mat and the glass bottom? Or does it need to be 100% flat?

Thanks in advance for any help. :D

I prefer to put my probe on the outside of the UTH so it is flat against the surface. And so I can move the probe if I ever need to.

I use aluminum tape to secure my heat sources instead of the UTH sticky stuff so I can take it off if I ever need to.