My opinion would be:
1., not necessarily
2., could be
3., release history should be part of the DHF, the latest released design to production is more like a DMR for me.
I think, one extremity could be is that you keep only a one page document listing all the document references those relate to the design of the final release of your device design and a single signature manifest that all documents approved and the design was authorized to be released.
But, that's purely an opinion, you should work out your own way.
Cheers