The answer to both questions is yes, I can get slightly queasy, if I'm doing something crazy. But the nausea I got with the Rift S was a bit different. It didn't matter what I was doing in the game, I would always feel a bit off for about an hour after removing the helmet. That's what I meant when I said it was the headset that made me sick.
This wasn't debilitating, and I would gladly have lived with it rather than pay a small fortune for the Index. But then, after a few weeks of ownership, I started suffering from infuriating eye strain. It soon got to the point where I couldn't bear to look at text in Elite. It was perfectly focused, but it just felt off in a way that I can't really describe, and was unbearable. That was when I decided that the Rift had to go.
I was baffled by the whole thing, because I had a DK2 before the S, and I used it for years without any of these problems. Then I read someone (Palmer Lucky, I think) saying that the DK2 lenses were much more forgiving for people with the wrong IPD. So that must be it.
Perhaps I'm just over-sensitive. All I can say is that, for the first days and weeks with the S, everything was fine and I was delighted with it. The problems only surfaced with prolonged use. It was as if my eyes and brain were saying, 'All right, we've had enough of this now!'