Hi!! First off, thank you for the comment!!
To answer your questions:
1) Yes. Almost everyone stims in some way. Stimming is basically any repetitive movement that provides sensory stimulation in some way.
I think the difference is that autistic people, people with ADHD, and people with mental illnesses stim more than the general population, but yes, I think most people do stim in some way.
2) I know some pretty common stims that are more normalised are thinks like pacing when nervous, biting your nails, twirling your hair (altho this is somehow correlated with flirting?), bouncing your legs. Things like that.
3) Ah I have the same problem. For me the best thing is to keep my hands busy, and if it's sort of an oral stim, you could try chewy toys! There's actually heaps of different ones you can find online. (Stimtastic.co is a really good website). And some foods can be good too, like hard candies, or crunchy foods.
I hope this helps!! Feel free to message me if you have any other questions or even if you just want to talk!!