Yes to all this.
I just purchased the DVD edition of the cult 1973 Robert Fuest film "The Final Programme." Apart from a beautiful presentation of the movie in the correct screen ratio, the DVD includes a great commentary with the director (who also wrote and designed the movie) and Jenny Runacre who was the female star. A group cast commentary for hoDS and NoDS would be a wonderful idea.
I also love the idea of a stills selection. Another extra that would be wonderful is if any video footage could be recovered of the many TV interviews Grayson and Sam did in a tour of the country in August 1971. I suspect they're all gone, but if any do surface, what fun to see this as part of the movie viewing experience.
G.