Everything. I've been taking lessons since I was... well, it's been 8 years since I started so I think that would have put me at 6 when I started. We've moved around a bit so I've had 4 different piano teachers. And all of them were very different. The teacher I have now focuses a lot on the technical aspects of piano - poise, expression, dynamics, etc. and I've learned a lot about theory and playing since I started taking from her 2 years ago. Mostly I like to just sit down and play whatever - improvising and letting my hands take over. It is generally reflective of my mood and feeling, but I LOVE doing it. That's really cool that you play at your church. My pastor has asked my dad to play (or me to accumpany my dad on the guitar) and neither of us are keen on doing it.
Yes, yes - I know - chicken but I always get terribly nervous playing in front of a lot of people.