I studied (classical marimba) with a guy who treated all those unnecessary motions that most musicians make as performance skills. He was no fan of spontaneity on stage, but also realized that the audience will enjoy the performance more if it LOOKS like the performer is being spontaneous & is moved by the music. So he would actually rehearse every motion that he planned to do on stage - even the ones that had nothing to do with the music. The most important thing is to know WHY you are moving.
I have to tell you that it works - his performances are brilliant. It works, because people tend to mimic what they see - and if they see the performer "carried away by the music" - they will subconsciously join in.
As for the humming - don't worry about it. You're in the company of many great musicians (Glenn Gould, Oscar Peterson, BB King, etc.)
_________________
"I am likely to miss the main event, if I stop to cry & complain again.
So I will keep a deliberate pace - Let the damn breeze dry my face."
- Fiona Apple - "Better Version of Me"