84% have published at least one first-author paper in CNS or a CNS-family journal (Nature Genetics, Science Signaling, etc.).
Unambiguously, no. I've collected similar data for several years, and I consistently see that 20%-25% of candidates have a K99.
No - but it probably helps. At some institutions, 70% to 90% of interviewees have a CNS paper. I of course don't know what the base rate is in the applicant pool, but I'd be surprised if it's 70+% CNS.
Yes - I think that this data suggests that candidates occasionally get interviews based on the strength of a preprint. For instance, candidates 27 and 41 seem to have their "major" postdoctoral papers up as preprints, and they received interviews.