Hehe, that makes second ASCII advice (first was mine according to one of the users).
I didn't quite get it though. can you post a snapshot to what you mean? If you've got a model which loses detail when you delete vertices then there's something you obviously need to fix.
For snapping you've got the 'use snapping points along edge' in the split polygon properties. also you can use MMB to relocate the last vertex and in this case you can use all snapping options such as snap to points, to grid, etc.
Benny