New to this

I attended a job fair last week, specifically for soon-to-be RN graduates. During this job fair we were interviewing with hiring managers from different hospitals/units within this particular health system and in some instances were given our second "peer" interview at this time as well. Now I am a bit lost as to what happens after this. I've sent "thank you" e-mails out to those I've interviewed with and I know that it will take some time for them to make their decisions. (Most of the spots are for residency programs that will not start until August.)

Say I am offered a position at one of the places I've interviewed with - do they typically call or e-mail with the job offer? Do they usually give you a certain length of time to decide before you accept the offer?

This is all completely new to me so I have no idea what to expect. I'd appreciate any advice you all have to offer as well. Anything you wish you would have known while job hunting or before accepting your first job?

Thank you!