TDY is going to be hard to come by with ASA with so little stations since the merger with DL/NW. I had a position with ASA that was possible to do a lot of TDY, I even TDYed in a OH station. Pay is probably comparable and ASA has the edge with flying benefits from what I hear 9E have. With the merger of XE I would think there would be better potential with EV.
From all the airlines I've worked for all have an agreement that you cannot work for any OAL, so in short you couldn't work for a combo of 9E, EV and DL.
For DL and ready reserve you are capped at 1300 hours per year. Starting pay now is 10.82/hr with it increasing to 11.07 in Sept...but depends on when you were hired and would eventually go to the latter. BTW you do not get a yearlying raise with ready reserve. You get good flying benefits but nothing else. DL is much more competetive when it comes to moving up IMO.