I would focus on critical care nursing materials for now. That is the base to build upon later as you prepare to apply to CRNA school. There are alot of good books out there, but most would probably be a little beyond what you need right now.
All through RN school, anytime I was in the OR, I would definitely get up at the head of the bed next to anesthesia. Talk to them while you are in the OR, get advice about a good ICU in the area to try to start out in.
Once in an ICU, after you start to feel competent and meet the time requirements, start studying for CCRN. Studying for that exam really helped in the interviews.
Good luck with the adventure