I also have an interest in wilderness survival. I like your lists and I agree with the first 2 items on both, but I think that Shelter (Shade is shelter in a hot weather situation) should be third on both lists.

I think of it in the rule of 3s. 3 minutes without air, 3 hours exposed (to excessive heat or cold), 3 days without water, and 3 weeks without food, before your body suffers irreparable harm.

Many people survive cold nights when hunkered in a sheltered area witn minimal insulation (i.e. clothing) and no fire. Once the shelter is secured, it can be enhanced with a fire. Then signaling to help SAR find you (either electronic or otherwise, maybe the electronic before the fire if you have a sat phone or cell coverage - and a fire is a signal).

Water is important, especially in a hot situation, but if you have shade you could survive for a couple days waiting for SAR without water. Admittedly, it would not be fun, but if you are in the desert (like I am) you'll waste way more energy and stored water looking for a water source (that you may never find) thus reducing the time SAR would have to find you alive.

I think that both lists are actually the same (you do not include fire on the hot weather list but even then a fire is important for morale and in the desert, the nights can be quite cold even though the days are hot). Food is definately the lowest priority.