I am a 4th year at the school. I guarantee you that I eat more meat and drink more caffeine than you do! Seriously, though, SDAism is not nearly as widespread as people think. I really believe that people use SDA status to improve their chances of getting into the school. Sure, you have a few hardcores, but for the most part the class is surprisingly normal. People do drink alcohol, eat meat, and drink caffeine. (They even cuss and have premarital sex--yikes!), What you have heard about hospital employees is true--most of the residents and nurses are not adventist.
There are still some minor drawbacks, however. While there are no rules on diet, the cafeteria does adhere to an SDA diet. You can eat meat; you just can't get it at the hospital. (There is caffeinated coffee at every nursing station, so don't worry about that). Also, many of the attendings are very religious. So while it's okay for you to go to bars and nightclubs (if you like Hispanic chicks with blonde hair and fake tits, you'll love the local club scene), it's probably best not to discuss it with the attending. Most of the residents adhere to the "don't ask, don't tell" policy in this regard. Even this is variable, though. It really depends on the department. Anasthesia, for example, is known for its very laid back, "normal" attendings. In contrast, family medicine attendings tend to be ultra religious. I notice that you are going into radiology. I don't have much experience with the attendings in that department. I think if you really want to do radiology in California, though, I wouldn't pass up the interview offer. I believe that we are one of the lesser competitive California schools. I've heard that our accepted classes generally average around 240 Step1, and that there is not extensive inbreeding.