NKC hospital preemployment physical

I will start at NKC in a few weeks and must go for a physical next week. I hate going to the doctor and only feel comfortable with my own physician. Can anyone tell me what to expect. do you have to put one of their lovely gowns on. Can they refuse employment if they find something wrong or will it affect my insurance in the future. If anyone can help me ease my mind about this i would really appreciate it. Thanks.