What route are you flying? I don’t like your odds. I had a recent flight that was J8 two days out and everyone ended up buying up. No one got upgraded. But that’s not always the case. If you really want it, you should pay for the seat

for the buy up, I think you might be able to call and ask, but I’m not sure. I usually just remove the pluspoints and reapply afterward. It’s rare that time of request is actually used as a tiebreaker (or at least that’s what I assume anyway)

I don’t think they will clear anyone’s upgrade as long as you are at the top of the list and have not consented to split the reservation (could be wrong)