100* is way too hot. That is enough to burn your snake. 90% humidity is way too high. Shoot for 70% humidity during shed.

What do you mean by light splotches? That is not a normal indication of an upcoming shed cycle.

Eventually you will learn the signs of an impending strike. Unless your snake is curling into an S shape and hissing at you, there is nothing to worry about. If you are worried that he might be getting ready to bite, poke him on the nose and he will probably just ball up. Thats what I do to my snakes.