1) I think I would like a "zoom to selection on change" option.

2) CAESAR does, in more recent versions, when you click on the global coordinates tool. It shades disconnected nodes green.

3) This one is a little more tricky, I guess. You can apply a displacement to a CNODE that's not in use in the model, so it'd be more complicated than to check just the nodes being used. I agree a warning couldn't hurt.