Keep the graft point above the soil line. If the trunk roots in, the tree will not follow the growth pattern you expect from the rootstock. The rootstock determines the tree size.
It's best to plant in cooler weather, not the heat of August, but it's still do-able.
If your soil is really dry, water the site heavily a day ahead of time and let it soak in. Dig hole, stick in tree, backfill it and tamp it down gently. Water, water, water. If the soil sinks around the roots, fill it back in. Water it frequently.
Google or look on tags or in a book to see how far apart to plant them (based on type of tree and how big it gets.) Fruit trees need at a minimum 6-8 hours of direct, uninterrupted sunlight, so don't plant them in a shady place.