You'll have to be doing pretty well to get to Cray before grouping, although obviously lots of people do. The grouping time is listed in the rules, I believe. It's a safety thing so they aren't flexible about it, which is fair enough. Having said that, they usually announce at the CP's that they'll start grouping in ten minutes or whatever, so you can scoot at that point and then get grouped at the next one. (probably with the same people you scooted away with!)
The date clash is just an unfortunate thing that's happened due to the land use issues the Fellsman team have had with new land owners. Unfortunate, but can't be helped.