Watched the parts you mentioned as you were pretty clear about what time stamps you wanted help with...

A few comments:
Yes, you kick the centerboard up/down with the foot, just like you did. Downwind, it's likely fastest to have it all the way up but you aren't racing and you are correct - having it part way down does add stability. When you get to the planing section of your learning curve, you can kick it all the way up. Don't try to plane with it all the way down, it generates a lot of lift and will literally flip the board over.
Yes, we are asymmetric - usually we can ignore it but activities that require us to use both sides of the body reveal it. Be aware of the strong/weak side of your body and how your stance, etc will be affected by it. Notice your hand position (e.g how far down the boom), foot angle, everything. When I started foiling, I was shocked how different I was side to side even after windsurfing for a couple of decades.
Some people prefer a slightly higher boom on longboards. You might try raising it to chin level Gestalt makes a good point about the front foot. Also, over time, try to keep your feet no wider than shoulder width around the center of resistance. You'll feel more relaxed.
You are correct to be wary of oversheeting. You'll begin to get a feel for sheeting in just enough and not stalling the sail. Do remember that unlike sailboats, our sails rotate around the center of effort. Pushing the front hand out and pulling the back hand in both sheet the sail in. When you are close hauled, remember to keep your front hand straight and away to keep the sail in. You looked like you were doing a decent job of this already but it's a good concept to understand.
Looks like you were having fun. And, yes, TOW is the great educator. Go out, have fun and you'll be more relaxed and a bit better each time. Hit us with more questions as they come up.
Many of us around here have the attention spans of squirrels.

If there is something specific - maybe just post a quick clip or two of what you want help with . If you need a video editor, try this open source program:
www.openshot.org/en/download/