Your main concern having heat tape actually in an enclosed tank is water, if your critter spills enough water he/she could very easily cook themselves
I would highly suggested radian heat panel. they are fairly cheap in the usa, can be side or top mounted and water proof
If you insist on heat tape, you'll want to grout/tile in the panel, the same as you would do a tile floor/infloor heat
(I actually use heat tape for in floor heating in my bathrooms, a beefed up version but same thing)
LED lighting works great,
For the vents, get metal and adjustable flow versions. seal them in good. dont rely on screws only. use silicone
the opening method works. just get really good locks
