It will be okay! Even though you have been a nurse for a while, they will mostly treat you like a new grad, as well as asking/observing to see where your skills are. They do not expect you to be an expert at this pt population, or all of the meds, monitors, devices, etc. Sometimes getting back into the 'student' role is a little difficult, to be told 'no, we do it this way...' or whatever. Just take it in stride. Always ask questions and continue to look things up on your own.
I always liked looking at the AACN procedure manual, they should have one on your unit. Also, after orientation, you can get a ccrn review book at the library if you don't want to buy one. A wealth of info on this population. If you are doing cardiac surg, there are a few great ones out there like the 'manual of perioperative care in cardiac surg'.