Even though it appears that the tree can stand alone, keep the stake for at least a year to help the tree stay straight during heavy wind and rain and perhaps ice. Re: height & width, Red Dragons will have a tendency to grow far more wide than tall tho it is said that if you keep staking a central leader, more height is encouraged. Re: the hole, since my experience with Virginia gardening is clay soil, dig a broad shallow hole so that perhaps a third of the root ball is above grade, mix half the clay with soil conditioner (which is fine pine bark where I live), and mound the soil so that the sides of the root ball are covered. Do not cover the top of the roots with soil but do mulch well with pine straw or whatever is available in your area. The roots will eventually extend far beyond your hole, but your efforts will get your tree off to a good start.