Kevin, welcome. Agree that the M80s have enough bass that the EP125 wouldn't be a major addition, so if a substantially stronger sub isn't to be used now, go with the M80s alone.
Your 2809 will be fine for all safe(to your hearing)listening levels.
You haven't described your room setup, and I might suggest a different center, such as the in/on wall M22 if it can fit.
As to the wire, study Mr. Russell's excellent discussion, which Tom linked. If at this time you're only considering front speakers with relatively short runs, that thin wire may be sufficient. Something more precise than "maybe 20 gauge" would be helpful to know, so if you can compare the end with something else of known gauge, or cut off an end and compare it at a hardware store, do so.
This raises a question as to why you haven't mentioned side surrounds, which can add a great deal to all music and movie program material, especially if QSs are used. This should be an immediate consideration.
