I'd thought about all of these things, but they didn't seem likely to me. At least, not likely to work more than a couple of generations. There's no way it could possibly work efficiently enough and fast enough or long enough to hold off the Dominion for months. First of all, the idea of them being able to "capture" and use explosive energy from nearby mines like that doesn't jive with what we know about their tech. And remember, they couldn't just rely on capturing energy and matter from destroyed ships, otherwise they could have simply sat back and fired a bunch of torpedoes and taken down the field from a distance. So how do they explode, expend energy exploding via light and radiation, have enough of that energy be "captured" by surrounding mines, and then have enough matter and energy to perpetually replicate more mines? See what I'm getting at here? It's a relatively closed, inefficient system. It violates the laws of thermodynamics as it's presented. It would be like building a perpetual motion machine.
It's an interesting idea that seems to work on the surface by combining a few different Treknologies, and since it works on screen, well, it just does. I think I'm just going to say "plot magic" and move on.