DEN is by far the most senior base, but also by far the largest base. If you want it, I think you'll be able to get it soon after if not in training. That said, reserve is lasting at least a year right now in all bases. Captains who have been here 11+ years can't hold DEN at all. You might consider that with upgrade times currently in the 3-4 year range. We are expecting growth but you have to take that for what its worth. Only a handful of airplanes to be added this year but there should be a lot being added beginning next year (per the company). I hope a new contract is close, but I don't expect any significant progress until the company begins to have a hard time staffing.
Reserve life is dependent on reserve period, base, month, staffing, etc. - hard to tell, but I imagine fairly typical of the other ULCCs. Long call is 12 hours, medium is 10.5 hours, and short is 2 hours. Rumor is they might provide hotels to future newhires, but plan for that not to be the case. Total newhire training footprint is about 2 months so expect that in hotel, airbnb, rental costs. I paid around $600/mo for a room during my initial. Having a car there is basically a necessity.
I like the job but I sure hope there is a new contract soon. Expect no more than $33,000 on your W2 for the first 12 months at current rates (maxing out the 401k match).