RE: planting throw and grow food plot
How big of an area? If it is fairly small, a pump sprayer with Roundup will take care of the grasses (wait until it is a little warmer and the grasses are greened up). Then either rake the area up or better yet take a harrow drag behind a tractor or ATV to get up the dead grass...that step might take a few passes.
After that, you could use the manure...its cheaper than other fertilizer, plus the throw and grow mixes probably wont need much for fertilizer.
Good luck and let us know how it turns out!