I ask you the following things:

1.) How I can inside ADD PAINT OBJECT, only to select the vertices that I need? For example I have created an object like a worm, with the curved tool and has several points, I need to only move between keyframes some points, to simulate the displacement animation.
I have used move 1 point, but this is quite difficult, since I must again fit the position of the points. Im Working in Way New Animation.
2.) How I can obtain Show onion Skin between Keyframes, within New Animation?
Thanks in Advance.