Certified GKH Gardening Expert
Burning bush shrubs are on a lot of invasive plant lists. The berries are eaten by birds and distributed. It is widely available for sale, however. It's not considered a fast-growing shrub and I'm not finding it on any lists of shrubs that deer avoid. It also is not evergreen in your zone 6.
The height and width depends on the cultivar you choose. There are dwarf cultivars you may want as well as those that can reach 9 to 15 feet tall. Once you know the mature height of the plant you choose, space them accordingly. For example, for medium shrubs, space them 2 to 4 feet apart. Plan so the widths will overlap.