Good God. I am on mobile but will still try to answer the things that could be answered by simply reading.
1. Yes. I am aware she is stronger in her second key. It was specifically chosen because it was realized she could not contend with Charon in her first key. However, she is 4-D in her first key, whereas Thanos is not. How the hell did they have a fair match?
2. I have reiterated over and over the potency of the BFR. You have repeatedly either ignored it or relied on getting an irrelevant answer from an irrelevant staff member to stave off this reality.
The hole isn't a portal, though. The way Qawsed explains it, it just cuts out the hole. The Far Realm encompasses reality- we're essentially in a bubble. This would remove the part of the bubble you inhabit. I don't see how you can understand that and say "ah well verse equalization ig". Either she resists or she doesn't, this new point is solely wasting time.
3. I am aware that all Servants have 4-D stuff per the wiki. That was, in fact, my point.
4. Say wish -> Wish happens. "I wish to cast spell". He can avoid her until then. He has an intellect that rivals gods and can teleport/travel between dimensions. Her bloodlust is noted but almost certainly not going to stop the wish.