I did an exchange to the Naval Academy a few years ago. The basics to know are if you're interested, you need to apply. Squadrons normally send out e-mails near the end of 3 deg year (for fall exchange) and midway through the first semester of 2 deg year (for spring exchange). You write an MFR explaining why you want to go (many people have drafts already, so its not hard). They then select people to interview. After the interviews, they select who goes, and for an entire semester you attend the sister academy (Navy, Army, or Coast Guard). You live at their campus, take their classes, participate in all their training, but still wear your uniform. It's definitely an eye-opening experience, but one of my favorite while at USAFA. If you have more questions on it, let me know.