I'll add what I can.
Not sure what the callback time is currently, but I do know that we hired nearly 300 pilots this year, and at least for awhile, it was moving pretty quick. Looks like with the E-170 deliveries and the remaining 145's, there should be at least another 200-250 pilots hired in the next year. I'll add that SDF is also a fairly junior base, which should be taken with a grain of salt. Right now, pretty much any 145 base with the exception of PHL and RIC, you would be able to hold within a few months, and most likely hold a line quickly as well. Most of the recent newhires are sitting one maybe two months of reserve depending on where you are based.
As far as QOL, there is the same bitching that you will hear anywhere. However, we do have pretty good working conditions. The pilot group and the flight attendants seem to get along much better than most of the other airlines that I have flown on (and I've seen pretty much all of it commuting), and most guys, again depending on where you are based, can hold 15 days off a month no problem.
Another nice benefit (subject to the company's whim) is our many bases. Some may disagree, but if you don't like commuting, having a bunch of bases gives you plenty of choices. Currently we have ten bases, but as I said, the company can randomly close bases (BOS for one) when the route structure dictates. My feeling is if you can't be happy at CHQ, you're probably not gonna be happy at any regional. I've worked for another Delta Connection regional, and can say that CHQ is a great place to be given the current state of the industry. You may not be moving on for awhile if ever, so let your decision be somewhere that you can be happy. Personally, I enjoy working here, and feel like I could make CHQ a long term destination if no better opportunities exist in the future. Best of Luck.