1- what happens if there are keyframes within the bump interval? It
seems to me that they become bump keyframes too, so the interval
designed by us is reduced to several intervals between close autos.
That is correct.
2- When you set the right edge keyframe (edge and span), you also
change the left edge keyframe. And vice versa. In my opinion it would
be better to make them independent
Turn off span and you should be able to do that (I have not had a chance to test myself).
3- The autos handlers give boredom, confuse the curve if there are
other keyframes and are unusable to make changes to the autos (which
can only be done with sliders). Is it possible to delete them or at
least not see them?
I agree and am still trying to convince GG to turn them off as they just confuse me.