Very short and very easy answer is, replace that mic. The rest of your gear is perfectly fine for what you want to do, though of course, your budget will inform how many and what upgrades you want. The weakest piece of gear you have is that Sony single-point stereo mic, by far. A basic set of $139 Church Audio mics will vastly improve your recordings; there are used mics in the Yard Sale for even less, like AT 853s as well as some Church mics, that could do the trick. But again, it depends what you want to spend.
Assuming you record loud shows mostly, you'll just need a simple CA-UBB battery box ($39) to power the mics. I think your thought of going CA-14 is a good one in your price range.
The M-10 is a very nice deck, much better battery life than what you have, but it won't improve the sound of your recordings nearly as much as the change in mics. Any small deck that is functioning will probably work, but yes, the M10 is the best of the lot. I just recorded an entire festival (16hrs music) plus a wilco show, plus a few other shows, and my batts are still showing 100% full. The battery life is uh, amazing.