Cow manure is not a mulch, though it's a wonderful soil amendment. My dad grows in pure composted manure spread on top if his lawn. But if any weed seeds blow in they will love it as much as the veggies. Best cheap/free mulch I've found is newspaper weighed down with burlap. Last year I used hay on top of burlap, the hay tends to blow away and the burlap decomposes within a year, newspaper takes longer and will blow away. Ants tend to build nests under the burlap but the worms love it too, this year I pulled the decomposed burlap off and left the sides of the mounds exposed, put what little hay I had just around the plants (didn't want to hold a lot of moisture in, June was so wet), didn't replace the burlap and the weeds (crabgrass, ragweed, and bindweed) are terrible, I'm going to have a big cleanup job when harvest is done. But for strawberries the best mulch really is straw if you can find it (and I thought $7/bale was high!), in my zone I use leaves and pine boughs to cover for the winter. I got small bales of straw on sale last year after Halloween, also that's the time of year to ask on Freecycle and Craigslist too. Leaves just mold and cause mold/disease on the plants when used in strawberry bed. Pine needles might be good alternative to straw, I just don't have enough clean ones around here with the oaks and maples mixed in with white pine and hemlock.

That's a good point about the sawdust canceling out the N gained by the manure. I don't really know the science of what is happening, but I am having a much better garden year then ever before (knock on wood), so will repeat the steps next year and hope for a similar result plus manure is cheaper then blood or cotton meal. The stout method does encourage us to lay it on thick enough to cover anything (except whichgrass), so seeds really have never been an issue for me. I even let dandolines go to seed without worry. Stout also encourages you not to worry about weed seeds - and just get the cheapest, most easily available mulch you can find. Some of the manure I put right on top of the hay and then added more hay. In the areas where I put my heat loving crops I remove the mulch in early spring - and then dumped the aged manure directly on the soil. When I put in my starts or seeds, I re-mulch. I'm in upstate NY - so it would take a tank of gasoline to light my rotting mulch on fire. I would guess that dry places would benifit from the mulch even more then I do - nothing looks more harsh then crusty baked naked garden soil to me these days.

I have used straw for mulch many times, but not usually alone by itself. In the fall I collect all of our fallen leaves and chop them up with the mower. I combine that with used straw from the chicken coop, and also grass clippings from the summer mowings. So right now the main mulch in the cutting garden is grass clippings. In another month or so the chopped up leaves will go into the mix - and the used straw from the chicken coop. I've used "fresh" (non-chicken coop) straw as well, but I run it through the mower first so it breaks down faster. The beds are covered with this mixture through the winter. For annuals that get planted in the spring I uncover the row areas I need to warm up the soil a bit before planting. I've never seen voles here but we do have the shrews others were talking about. Thankfully their main diet is not vegetation. Our cats bring them to the back porch as "presents". :) There are still some weeds that pop up around the edges, but thats about it. The layers of built up mulch keep the rest at bay - and build good quality soil at the same time. If you don't have access to a lot of grass or fallen leaves - offer to pick others up from the curb. I cringe when I see all those bagfuls on the curb for the trash man to take. I've helped myself to many in the past! :)

I use the plastic edging around a garden that's on a similar slope in my yard to keep sheet water from flowing through and washing out the mulch. Given your neighbors' yards appear to be draining through the area and the amount of rain you get in NC, I'm betting you have a lot of water rushing through there at times. BUT if you completely blocked off the whole area with plastic edging, it would flow right over and do absolutely no good (not to mention ticking off the neighbors in the process). Therefore, you could divide the area into three or four beds, leaving at least a couple feet in between to allow water to rush through the grassed or rock channels. You can then mulch the beds without too much water running the gardens and washing out the mulch. I don't know how much water comes through that area, so I'll leave a necessary size of the beds and channels to you. This may not be the most aesthetically pleasing way to do this but it may help keep the mulch in place. If you do go through with this, be sure to watch the edging you buy. At least one big box seller with orange aprons, in addition to its cheap stuff, offers a "professional grade" in a larger bundle that's of much much better quality (taller, thicker, heavier, more rubbery) for not much, if anything, more. In addition to lasting longer, it's a lot easier to install IMO.