Silas, welcome. Your first step, getting the M60s, certainly would be a substantial improvement.
Replacing the 1018 would seem to be more for the bottom of the list, if needed at all. Depending on the sensitivity of your present speakers, the Axioms, which are of average sensitivity, can work just as well with the 1018 to provide sufficient loudness levels.
Your diagram appears to indicate that you're proposing a somewhat diagonal arrangement. If so, this complicates the placing of the surrounds. Side surrounds, which should be QSs, are supposed to be directly to the side of the listening position(5.1 surrounds aren't "in the rear"), but an adjustment to this would be needed to keep an overall diagonal concept between the speakers.
