Yup. Made me feel a bit uncomfortable. Me, an introvert

I would never do that. People also notice the strong practices around them without attention being called.

Yes, especially where I did my training in India. It was a very common practice in India and not really weird or uncomfortable. I'm not shy in front of people either so there's that to consider, but if it was something simple, an Indian teacher (who is verbally instructing and not on their mat) will often say "so-n-so pls demo" or if its alignment they'll ask you to do it, ask for feedback from others and then teach the correct alignment and highlight the difference as you demo.

Yes. I am totally ok with that :)