First and foremost, I'm more of a "controlled sound effects" player than a melodic player. At times I'm playing my effects setup as much as (or even more than) I'm playing my Theremin.
1) Do you sit or stand while playing?
Standing. Any time I try playing seated, I end up standing pretty quickly.
2) Your pitch and volume techniques: Do you use a fingering technique similar to anyone else? Do you move your body toward the pitch antenna or just use arm and finger movements?
My pitch technique is all wrist and arm movements (no fingering).
I hold an on/off switch in my left hand and my overall volume control is mostly just how close my left hand is to the volume loop.
3) How do you like your pitch linearity: non-linear like a stringed instrument or linear like a keyboard? Do you like wide octave intervals that require some arm movement, or octave intervals within the reach of finger and wrist movements?
I'm not really sure how to answer this one. It's not something I really think about.
4) What insights do you think you have developed in your playing? I'm talking about perhaps subtle or even subconscious things that are deeper than the simple mechanical fundamentals.
I prefer plating along with other musicians over playing solo. To me, the most important thing is to be able to hear all the other instruments I'm playing with so that I can mix what I'm doing into the overall sound of the piece. Most of the bands I've played with don't have a keyboard player, so I try to "fill the space" that keyboards would occupy.
5) What recurring difficulties do you have, such as pitch wandering, overshoot/undershoot, coordinating volume and pitch, etc.
The issues I have along these lines have more to do with getting the echo pattern I want than with Theremin specific issues.
6) Approximately how long have you been playing the theremin?
23 years.
7) Do you play other instruments? Have you had musical training? Again, don't be humble.
I played trumpet and baritone horn all through middle school and high school. I can play guitar (a little) but never really considered myself a guitar player.
8) What kind of music do you play? What motivates you?
Just about any kind of music can motivate me. I'll play along with anyone that wants to play with me.
My band is an instrumental/improv band. I played in a punk band for 2 years (yes, a punk band with a Theremin player). I play with some friends' bands every now and then - rock, surf, jam band, garage rock...
9) Anything else that you have to say about playing the theremin.
Playing Theremin has changed my overall approach to playing music in general and has definitely affected how I listen to music.
The Theremin has allowed me to go to places that I would never have imagined getting to without it.