1. BED_LEVELING_METHOD is how you measure the tilt of the bed. All methods return a optimal plate depending on the measurement method. You need 3 points but more help if you have some measuring errors or bed is a bit wavy to get a better overall plane.

BED_CORRECTION_METHOD is the way you correct the computed rotation. Software or mechanical side. Botha re independent and you can mix any combination that your hardware supports.

2. It always goes back to starting height so start deeper. Probe bed distance is the distance it does when homed under some conditions otherwise make sure you start within that height to bed. Apart from this change the xy or z probe speeds.

3. You can not really fix this. It has to do with the nonlinear motion splitting moves into submoves and the fact that we do not change speeds for started moves. So what happens is a move is e.g. split in 3 moves and movement starts on first move. As move 2 and 3 were not there at start oath planner said to slow down at and. When move 2 is added is sees move 1 is running so it can not change that move and must start from low speed. Only solution would be to always add a longer wait before first move but then the first move would wait a longer time before starting. So these pauses are no bugs just the result of how it works. In real print you do not notice as the buffer is at some point full so it always can get up to speed. But here you always start from paused so longer moves will always show that.