Re: Aluminum Foil sides
The finish on the aluminum foil does in fact make a difference in my experience. It's much like the difference between a satin black and a matte black surface on a sunny day.
As an experiment, next time you're baking cookies, cook one batch with the shiny side up and one with the shiny side down. You'll find that the batch with the cookies in contact with the shiny side of the foil are quicker to scorch on the bottom.
That said, I'm not sure that the difference is significant enough to notice when smoking hookah. Everything heats up as you inhale and cools when you're not inhaling, so I doubt that the small difference in heat retention via the foil is going to make much of a difference.
For myself, I almost always use my foil with the shiny side down, unless I'm smoking something that burns easily, where I'll put the shiny side up. It seems to make a difference to me, but I've not done any rigorous testing, so I'm willing to bet it's largely a placebo effect.