I'm not sure how they're booking travel however If I were to guess I'd say that its on Skywest airplanes only. It could be Delta or United but I'd bet its still a skywest airplane. Slaphappy, if you look at your ticket see if it says "operated by Skywest" then you'll know. Like I said I'm only guessing, it could be mainline. As far as the time goes, its true they won't budge.
Now, about this group interview deal. We are really short right now and need people fast. We have interviews planned thru March so there is a huge push going on to get people in class. If you have a group interview, be it in SLC or anywhere else for that matter expect to be invited for a formal interview in SLC SOON! A buddy of mine did a group interview in LA and the very next day he found himself in SLC for the formal, (he just finished ground school) Obviously they won't hold it against you if can't make it that soon but remember, seniority is everything and you want to get in on the front of this if at all possible. That's not to say that getting in next March would be bad (remember this is a regional and people move on all the time) it just that now is better than later. Good luck all.