I am really looking forward to hearing Mark playing more songs with Bob on this tour, but in answer to your questions, here goes:
1. Even though I know of Mark's great respect for Bob, it doesn't alter the fact, for me, that Bob's voice is terrible these days, but that doesn't mean I don't like his songs, I do, very much and have done since '61. Seeing them playing together will add another dimension to the songs, though and make Bob's voice more palatable. So I would say, no, it doesn't alter my view of BD, but I do recognise his respect for Mark and so I respect him more now that he and Mark have played together at last.
2. It depends on who the guests would be. I'm not counting Emmylou, because she was jointly part of the show, but Gillian Welch and David Rawlings were nice on certain songs. I can't think of anyone at the moment, because I enjoy MK on his own too much really! I would certainly like MK to vary his set-lists more though.
3. Yes, bring it on, but I don't see how he would fit in, not even with his harmonica. It would be interesting to see, though.
What this collaboration does tell me though, is that as well as MK respecting Bob, Bob also has a great respect for MK, because from what I have read elsewhere, Bob almost never shares the stage with anyone, so that alone speaks volumes.
I would like to know what the more sceptical BD fans have to say now!