Houstonians: Can you help me understand A/C usage?

Sorry to sound naive but i have no clue on what to do with my air conditioner this summer. I moved to this rental house in October and i dont think we turned on the a/c much at that point. The house has a HVAC unit.

I read somewhere that im not suppose to turn in off ever? Is that correct? I have read mixed comments about it. I've read that turn it off can cause mold, other people says that its ok, etc.

When I leave the house and wont be here for hours, am I suppose to turn it off? Or to put it in like 80F?

What if im going to be out the house for several days? Should i turn it off then or not even there? Isnt super wasteful if i live town for a week and leave the unit on?