Can't say anything about watering the foundation, but leaving the garage door open about 8" to a foot can alleviate some heat in that your garage ceases to become a heat trap because there is some circulation of air when the garage door is cracked open. Same goes for the attic door. Don't know about the others.
Another trick, if you're willing to try it: put your windshield sun reflector (especially if you have the "foiled" kind) on the OUTSIDE of your vehicle. While still somewhat effective on the inside (it does keep areas shaded) the "heat" reflected off of the reflector is just bouncing straight into your windshield, but staying in the car. Putting it on the outside of the car reflects the heat away from the car entirely, resulting in a greater cooldown. It's not fool-proof, but it works.