I thought the survey looked well-designed, but I'm not sure it will get at the problems that need addressing. Mentoring is a very tricky problem for a number of reasons.
First off, the person in need of mentoring generally doesn't know what he needs to know. He doesn't know what questions to ask, or who to ask them. If he knew these things, he wouldn't need mentoring. He might be aware of his ignorance, but he doesn't know what the boundaries on it are. So it's hard for him to know that he needs mentoring.
Second, even if he does feel the need for mentoring, it's very difficult to ask for it. Saying "hey, I could use some help managing my career" feels like an admission of incompetence, and not only is that a very difficult thing to say in general, it's even harder to say it to a well-esteemed colleague who's very good at managing their career -- which is exactly the kind of person you should be asking for advice.
Being an early career person is often highly competitive, and a request for mentoring can feel like exposing a weakness, which is dangerous in a competitive environment. Not to mention the fact that, even though everyone says "oh, yes, we'd be happy to mentor you", the more senior people are all incredibly busy. It's difficult enough to interrupt their schedules for requests related to work; demanding personal attention for ill-defined feelings of inadequacy seems like it would be well-nigh impossible.
So I guess my point is that institutions in general and this survey in particular both seem to view mentoring as something that should be driven by the person in need of mentoring, and it seems to me that that is the exact wrong person to be asking about it: he doesn't know whether he needs mentoring, because he has no frame of reference; he doesn't know what to ask for, because that's what mentoring would be teaching him; he doesn't have the nerve to ask for it, because he's in a relatively new and insecure position; and he doesn't have the social standing to request attention from the people who make the best mentors.
I also think that most of those who are in need of mentoring will not have a high level of self-awareness about the issue; they'll just know that the subject makes them feel awkward and uncomfortable, and that they wish it worked better, but they don't know what's wrong.
I'm all about root causes these days. Instead of asking the people who need mentoring "so, what would make mentoring work better for you?", I think that if we really want more mentoring to happen, we should be asking the potential mentors "Do you mentor? No? Why not?"
(I ought to be using "mentee" instead of the phrase "person being mentoring", but I can't bring myself to type it. It just looks dumb.)