2) Let me try to break this down, also as an exercise for myself.

When using the outside edge and not having another foothold, push with your free left foot against the wall. This creates tension between your left leg which is pushing and your left hand which is pulling. This gives your more control over your body and therefore allows you to stay close to the wall.

From here you can use your right leg to initiate your next move: make sure it generates most of the power, while your left leg and arm mainly follow. Your left foot might slip if you put too much weight on it, and you obviously want to conserve as much arm strength as possible.

Whenever possible I would nearly always go with outside edge over inside edge, because the outside edge allows you to at the same time: a. Keep you center of gravity close to the wall b. Keep your arms straight and c. Have reach

You'd use inside edge mainly when you: a. Don't need reach b. Can't do an effective outside edge because i. The foothold and handhold are too far apart ii. You can't use the handhold from the side iii. You can't use the foothold from directly above iv. You're on a slab and turning and moving up would mean scraping the side of your body all over the wall

Is that clear? I don't know, let me know if you have any questions. (also, if anyone thinks I'm wrong anywhere, please also let me know)