I don't think the humidity spike will be a problem. They live in termite mounds in Africa which are sky high for humidity. I've knocked over the water bowl in my tubs and seen the humidity skyrocket as well. Just out of curiosity, what are you measuring the humidity with?
As far as where her head is when she coils, you'll find her laying in different positions sometimes. As to why she did it, who knows. She's a snake, doing snakey things.
Mine don't normally do anything in their water dish. I never see them drink, never see them soak. I wouldn't worry about her not going near her water dish.
At 270g she was almost assuredly born in July 2013, not 2012.
If you're hotspot is 85 to 88 you may want to bump that up a couple of degrees. 88 to 90 seems to be a good range.
You can make the hides out of almost anything. It's just something they need to be able to crawl into to hide. There's a thread somehwhere on this site of things people use to make their own hides. Litter boxes, flower pots, plastic thingies, etc. If you don't want to make your own, you can buy them...something like:
http://www.reptilebasics.com/hide-boxes