First off, 70F on the cool side is too cool. The coldest it should be is 75F and preferably 77-79F. Hot side should be 86-88F tops. I keep all my boas with a full cage temp of 77-79F and a hot spot with flexwatt of 86-88F. You can do 90F but dont expect to see your boa on the heat source much if ever. If you are using heat tape, you dont want anything deeper than 1/2 at most and you want to take the reading from the glass, not the top of the substrate. As for hides. I would stick to simple black plastic hides. They are easy to clean and cheap. I use these in various sizes. http://www.reptilebasics.com/hide-boxes
60% humidity wont harm the snake for a while but long term, yes it will. Boas come from a place with 70-100% humidity. You are doing the snake a disservice by subjecting it to lower than recommended humidity. As for shedding, you dont need to spike squat. I never spike during shedding and never had a bad shed. I keep my humidity on average of 70%. It does drop to 65% sometimes and i spike it to 85-90%. The boas LOVE when i use my pump mister in their cages. They all come out and are active for hours.
Again, temps should be 86-88F tops, not no less. Contrary to what some people think, snakes dont need to be kept cooking hot 24/7. Most snakes actually like it a little cooler and cooler is less dangerous to them than too hot. Overheating is a very common problem and a lot of people think IBD when in fact, they kept their snake too hot.
If he is on small rats, no way in heck should he be fed every week. The only time a boa should be fed every week is when they are under a year old and even there, some people disagree and say every 10 days. A boa on small rats should be fed every 2 weeks. Mediums every 3 weeks and larges every 4 weeks. Once on jumbos or rabbits, then you go to every 4-6 weeks. Rabbits are a lean dense meat so they pack more punch so you go longer inbetween feedings.