Diseases those may transmit to a healthy man while performing oral sex (cunnilingus) to a woman not well known to him:-

1. How they are transmitted, under what condition?
2. Name of the most likely diseases?
3. Most secured forms/measurements in performing cunnilingus?
4. Any physical indication that may be noticeable before performance - to determine the woman is healthy?
5. Medical advise so as to minimize possibility in getting transmitted?
6. Post performance medical examinations if any, to determine a man's health condition?

Thanks in avdance.