hello fellow texan

Two good questions! Hell-to-the-no on aluminum foil. Flat white is the best other than mylar. A lot of people don't do mylar correctly and it really grinds my gears. It has to be FLAT. I think mylar is about 95% reflective where flat white is about 90%. So really no real need to go there. Aluminum foil I think I read was only 30% reflective if that and it traps heat and is usually never flat in application.

A 24 hour light method does not hurt your plants and removes the need for a timer. 18/6 wont hurt it either. It's really your call there. Is the electric saved a factor? Or maybe you're running hot lights it might be a good idea to give everything a cooling period. People do both with not much difference in results.