Go to the AFPC website and click on the Retirements/Separations link on the left side of the page. They have full explanations plus links to the governing regs... but here's the short story -- you can extend your DOS for a total of 90 days (might be 180, but look it up to be sure) with no reason and without MAJCOM/AFPC approval, if my memory proves correct. However, in the current environment, I wouldn't be too keen on extending my DOS if I have a chance to get out and wanted to. You just never know when they might change their minds.
Reserve slots come open on short notice all the time and if stop-loss is ended, your prospective unit might have several slots available as the forecast for Reserve/Guard guys leaving is looking like a lot will be getting out, not wanting to risk activation again. I would keep current on their status, because it could change daily.
The best advice that I have received, from a Reserve 2star, is "be available". The best guy who can fill a slot right now will be the guy who gets the job. This also plays true for any civilian flying job.
Good Luck. Hope to see stop-loss lifted soon.