Thank you for questions 1 and 4, sorry I can't help you, but I have the same questions that you do. Also, when you say oral rapid are you referring to the oral fluid test? Thanks.
the ones that are just an oral swab i think they take a half our to turn up results
2) Not that I know of
4) Conclusive...it is conclusive at 3 months, so anything after is also conclusive