PBG preshaped bone nuts..

[Tindrrel]

This also allows for angle adjustment as well. (Higher at Bass end, lower at treble)

Do you mean sand the bottom of the nut at an angle to adjust it?

3. Slots are not evenly spaced. I cut the slots to compensate for the differing string gauges.
This compensation gives a more comfortable playing spacing.

How do you recommend aligning the nut if going to remove material from both ends? Centered, tend towards bass side or treble side?