1) this is an experimental feature - actually contributed by a developer here in the forum. Yes, it does exactly what you are saying - it allows you to specify the rect coordinates that the overlay will occupy in the atlas. While I hope not to break this when i do the atlas rework in 2.10, there is always the possibility that there could be an issue that requires changing or reworking this feature. 2) Sway bone is really simple - it just sways. It does no collision at all. The existing physics-based ponytail can do collisions if you setup the collision matrix, and add the appropriate colliders. 3) My guess would be about 6 months maybe? 4) This is a tough one - maybe get rid of all the .cs files, then copy everything over the destination skipping duplicates? Not really sure. Be sure to back up.