Is there a relation between slanting and vertical metrics?

Glyphs
1

If I use a 1 to 5 (11,31°) slope angle does it make sense to also set Cap Height, Ascender Height, and X-Height to values cleanly divisible by 5?

If not divisible by 5 won’t the letters be cut off right in the middle of a stair-step resulting in slightly uneven or blurry outlines?

2

This doesn’t make any difference. Strokes following the italic angle by definition don’t align with the grid, it’s just if you want to be absolutely certain that your angle matches.

Technically. If makes no difference and isn’t necessary. It’s just nice to have.