I"d put the rock in one 50 gallon tub and the sand in another and fill them both with water; this will use up most of your tank water (you could mix up a bunch of new water as well) Definitely you want vigorous water movement and a couple of airstones, or you could use maxijets with the little venturi attachment to get some air in the water. Leaving these tubs outside in this heat will probably kill all sorts of stuff, which would then load up the water with ammonia and kill everything else...sorry! You'll be okay without any light for a few days; you'll lose some coralline algae, but it will grow back.

I don't know what to tell you about your fish; I assume you're talking about keeping them separate from the rock and sand. Maybe a local store you've done some business with would agree to hold them for a few days?