Sounds great, you will have to put it in a perspex head cab so people can see the chassis

I think in answer to your two questions 1. No and 2. No the shells of a pot have no contact to the tabs and the two controls you mention do not require grounds. You only need to ground a transformer post if you were using it as a star for other components, the only other reason I could think of grounding a trannie would be to prevent shock if for some reason something major went wrong inside causing the shell to become live but I think this would be highly unlikely.