I work in a Cardiac ICU. Take the tele position and don't look back. They'll teach you there how to read rhythms and you'll get experience with chest tubes and various cardiac pathologies (and possibly ACLS?). Trust me it will make the transition to ...
They say you will get hired as an ADN if you agree to your BSN in 6 years. Don't know if they hold you to it at all, but I have met plenty of people with ADN's at Mayo.