My form and tight tick Charlie

Today's jump lesson was focused on my form, but John was very pleasantly surprised when he made an oxer just a bit bigger and all of a sudden, Charlie started jumping over it snapping his knees up to get his feet out of the way.  I've never felt him do that before - and then I had the great experience of getting to feel it a few more times - and it was similar to rounding and making a bascule, with lifted shoulders that kind of popped up.  John thinks it is because we used the elevator bit last week, and Charlie kind of caught on that he could approach a fence a bit forward but not on his front end.  After the first time, John had me halt and make a big fuss over him, and I didn't even know what it was!
The main take away I took from my form was that after the fence, I need to think heels down.  I also had my hands too high at the start, but that seemed to resolve itself.  I have to think about pushing them down and forward while I'm in the air, otherwise, they swing back a bit.  The other thing was to keep him going after a fence, and to look soon at where I'm going.
I had a couple good fences, and a couple corrections that I caught and made, but I'm still not reacting far enough ahead.  John said that a couple strides out I'll see the distance is wrong and do something about it, but if I could see it 4 or 5 strides out, I could do a half halt and fix it back there.  But the few that we rode well felt wonderful.
I also had a laundry list of questions for John, from his new shoeing (he has lines next to the nail holes and I was horrified his foot was going to fall off, but John said it is just a farrier style to set the nail head in), noted his dehydration (John agreed, but said that if his poop isn't crumbling and he's still drinking, not to worry about it, but to move his oat-water-bucket further away from his food), Charlie's diet (John thinks Charlie looks wormy and has no fat, so he suggested 1 cup of corn (or canola) oil a day, switch his whole oats to crimped or rolled, and add rice bran pellets), and whether I should ride prelim at the next Aspen derby (no, because it isn't the height but the technical precision, and we haven't been working on that so it won't do me any good to go there and be surprised by some two stride bendy line to a skinny, plus we need to work on narrows at home).
He said that we should do the elevator bit about once every three rides, agreed with me that Charlie had springier feet but was still stiff in his jaw, and said that if we focus on my form when Meg isn't there, it should help me get better with my distances.
It was a great lesson, but I'm too tired to repeat everything else in detail - these were just the very high points.