1) I think you need to assume that her infection is at least genital. Oral HSV 2 is not of much significance, but sometimes people do acquire it in both locations – giving oral sex to and having intercourse with the same person. So yes, assume she has genital HSV 2
2) There is no guidance on the risk of you acquiring HSV 2 by giving her oral sex (assuming no barrier like saran wrap, dental dams, etc. However, if that did happen, that you got HSV 2 orally, you would essentially be vaccinated against getting it genitally. Oral HSV 2 recurs very infrequently and is sheds very infrequently as well.
3) there has certainly been talk of that but on a basic science level, I’m not clear that it makes as much sense. It would likely require a very large dose of antivirals, taken often, to deal with the arrival of virus in the body of a person uninfected with either type of HSV.
I think the best move, if you want to start dating and having sex again, would be her taking daily antiviral therapy, you using condoms, she developing very sensitive skills to detect outbreaks (anything between waist and mid-thigh) and avoiding sex at times she might be having an outbreak, however subtle. Then you deciding it is worth the small risk of getting herpes to be having sex with her. I know you know all of this – you seem well read and informed. I think a false positive on the part of her ELISA is very unlikely but she could always do a confirmatory test I suppose.
Terri