I'll comment on heat and water.
I have hiked solo relatively comfortably up to 118F along the trail to the springs and back. It's dry heat so don't find it as exhausting as the humidity on the east coast. For me anything over 100F is the same, hot.
For water, we actually do not take water any more if we know there is a viable source at the destination. We carry the filter below which is more convenient compared to carrying water. Never felt ill after drinking water from many streams and lakes with this thing. I think I would be more concerned if traveling abroad but on our shores, this filter does it. You don't need to filter the water from the source feeding the pools, but it would still be a good idea to cool it off in the stream, or if you're imaginative, take some ammonium nitrate packs for an instant chill.
http://www.rei.com/product/858764/sawyer-squeeze-water-filter-32-fl-oz
On thing that does work if you want to cool off quickly. Take either a cold stream or ammonium nitrate and expose it to your inner wrists for half a minute. The blood vessels in that part of the body are close to the surface and absorb and circulate the cold. Something I picked up from my grade 7 home economics teacher to cool off in a hot kitchen, except we used to run our wrists under cold water from the tap.