Terms, Terms, Terms.

Lately here I've come across some terms I've not heard of.  I haven't had a chance to google them, but I'm sure eventually I'll get around to it. 
For instance I've learned that the hospital here in town offers a Critical Care Nurse Residency Program but I don't know what that means.  Yes I've talked to the recruiter but I'm not sure if its a good choice.  Also I was advised to take an Internship during the summer of my junior and senior year of school... what is the advantage of doing that?
Just about every job I see posted has the following terms CPR/BLS is Required and ACLS is Required  I get what CPR means and I think I know what BLS means, but the ACLS, you got me.
Also I was told it would be good if I got experience with the Critical Care units, but the hospital here also said if I could get a job as an Emergency Room Technician it would be great experience.
Plus I'm realizing that with my schooling I'm not required to take a class just for medical terminology, but that it will be included with my regular nursing classes.  However I'm thinking it may be a benefit if I could get a medical terms book or flash cards made to help learn common words or prefixes and suffixes. 
Too much to think about at times, it's overwhelming.