Probably

He took a far more powerful blast from Thor after receiving all of the gems but didn’t actually use them to tank it. All it did was stagger him for a couple of seconds and force him back a bit. He could probably take the blast with minor injuries.

Yes.

Depends how powerful that mind stone really is.

I think a big part of the reason for Thanos' success was the separation of The Avengers following Civil War. Not that Thanos planned for that specifically, but taking on the team in weaker chunks undoubtedly made things easier, and once they get back together in the next movie, they'll probably win the day (if they don't then the MCU would kind of be over). That three pronged teamup that melted Ultron is a prime example of The Avengers working together to beat a superior foe. For Thanos to withstand it, he would need to be stronger than Vibranium. Also Thor and Iron Man have gotten way stronger over those three-four years.

He takes it. The AoU combined attack was fairly lackluster to be honest.

He took worse from Thor