Some of these are interesting. I don't really think about what I do but I'm seeing some that I think I do at least sometimes, but usually in particular situations.
one arm across body clasping other arm by side (female) arms nervousness Women use this gesture. Men tend not to. It's a 'barrier' protective signal, and also self-hugging.
hand(s) on hip(s) hands / arms confidence, readiness, availability The person is emphasizing their presence and readiness for action. Observable in various situations, notably sport, and less pronounced poses in social and work situations. In social and flirting context it is said that the hands are drawing attention to the genital area.

I have prominent enough hips - it sort of feels natural to rest there?
Speaking of pupil dilation, I once had a temporary condition that prevented normal pupil movement in one eye and it was very, very weird, especially looking in a mirror. ( light hurts a whoooooole lot when your pupil can't contract properly).