Problems with WASP Delta 2040 head movement and endstops

Hello, does anyone have a WASP Delta 2040? If so, I need some help.

1. When I do bed leveling the space at the 3 points of height (indicated by the bed leveling option from the printer) is enough but when I move the head to the center it has almost no space. This leads to the head bumping into the printed layers when it reaches the bed center.
2. The printer ignores the M666 command (to set the endstop offsets from the Pronterface software controller) but from the inside machine control I can save the new offsets (with negative values).
Here are the numbers:
diagonal length: 295.5
delta radius: 175.1
3. Seems that the head is not perpendicular to the bed. It’s tilted a little towards the right.
4. There is also a bowl effect that the outer perimeter has in prints.

My questions are:
1. Is there any guide how to calibrate a Delta 2040 from scratch?
2. How can I accurately level the bed in this circumstance?
3. How can I fix the bowl effect of the outer perimeter?
4. Is there any way to fix the tilted head?

Thank you for reading