You can try the seeds but you'll have to carefully watch for males and remove those plants once you find them. As far as what strains they are it won't really matter. With the right growing conditions they will work.
I would dig holes in the ground and amend the soil with some good potting soil. Be careful with the cow patties. They're very rich in minerals and can burn the young plants and over used. A good potting soil will be good enough.
A fence is always a good idea with outdoor grows. All kinds of critters love the smell of cannabis. You'll also have to keep a close eye on bugs.