1) What is the likelihood of me contracting HSV from this one exposure?
I think low. The risks are the oral sex (receiving and giving) and the genital to genital rubbing.
2) If I were to catch HSV from this exposure, is it safe to say that I’d experience symptoms in the upcoming 2-12 day period and if I don’t experience any within that period then the likelihood is that I’ve been lucky?
Yes, I would agree with that statement
3) I am currently on antibiotics for a different issue, would this stop symptoms appearing if I were going to have a primary outbreak?
No, antibiotics are very bacteria and herpes is a virus.
Symptoms would not show up within 12 hours of encounter, no.
Terri