Welcome to the Forum and thanks for your detailed questions.  I'll do my best to answer your questions although as you have already noted, my responses regarding HSV-2 and risk for infection will be speculative as their are no data on this subject.

Regarding variation in guidelines, the variability as to whether PrEP would make oral sex with swallowing of ejaculate a no risk or "just" an extraordinarily low risk event is more a reflection of your web sites and the organizations attitudes as to whether one can ever say "never".  Science continues to search for new knowledge and new observations of previously undescribed events occur every day.  Further, every statistical statement is an estimate since very, very rare events might happen the next time an observation is made.  We know that properly taken PrEP reduces risk for acquisition of HIV to close to zero, we know that even among other men with male sex partners, most persons will not have HIV, and we conservatively calculate the risk of acquiring HIV from performance of fellatio on an infected person who is not on therapy is less (and probably far less) than 1 in 10,000.  Putting these together the risk for infection is i in many millions.  That is not zero but is becomes so low that it cannot be effectively calculated.  The analogy I have used on this Forum is that the risk associated with the hypothetical situation you describe is likely (who really knows) as low or lower than your risk for being hit by a meteor falling from the sky.  Abrasions on the mouth or oral HSV-1 would not meaningfully change this estimate.

As for risk for acquisition of HSV-2, this subject is has been far less exhaustively studied than the risk for HIV discussed above.  We know that when oral herpes is diagnosed, less than 1% is due to HSV-2, that even most exposures to infected persons (even in the presence of lesions) does not result in infection, and that HSV-1 does confer a modest degree of protection from acquisition of HSV-2.  Putting this together, my estimate is that your risk for infection would be lower than 1 in a million and probably substantially lower.  I cannot be more precise than that.

I hope these comments are helpful to you.  EWH

I'll try to answer your questions briefly but we have to limit the extent of our replies.  Many of these questions would be more appropriately discussed with your own health care provider:

1.  Your summary is correct.  I would have little concern about performing oral sex on an infected partner.  I would add that if you are talking about performing oral sex on your HIV+ female partner, your risk of infection is likely lower than for performing fellatio on an infected male partner. 

2.  HIV-2 is so rare that there are few data on its utility vs HIV-2.  I can think of no reason why PrEP would not also prevent HIV-2, as well as HIV-1. 

3.  There are no interactions between ceftriaxone/azithromycin for gonorrhea and benzathine penicillin for syphilis. If you happened to acquire both infections at the same time your could be treated with both first line therapies.

4.  Yes, doxycycline would likely prevent chlamydia and syphilis most likely.

5.  There are no data on when it would be safe to stop taking PrEP. Further, it is possible that achievement of an undetectable viral load is a process rather than an event and there could, conceivably be intermittent viral shedding as the infected person becomes undetectable.  Out of an abundance of caution, I would want at least two undetectable viral loads OR at least two weeks to past before stopping PrEP.  Once off PrEP a 4th generation HIV test would be reliable 6 weeks after the last exposure

6. There are no studies of valaciclovir for prevention of HSV acquisition, 

7. Oral HSV-2 is so rare that there are no data to answer the question you are asking.  I would assume that you are not likely to be infectious through the sort of casual contact you describe.  I would avoid kissing persons if an oral lesion is present.

EWH

These questions are a bit repetitive  Repeating the questions will not change the answers.

1.  Agree.  FYI, if not on PrEP there is a likely hierarchy in which fellatio is a higher risk than either cunnilingus of analingus. With PrEP risk should be virtually non-existent.

2.  There are just no data to provide a quantitative answer.  Risk if very, very low.

3.  Correct

4. (new question.  Again, no data to provide a quantitative answer.  Very, very low

Thanks for your thanks.  As you note, this thread will now be closed.  EWH