Questions on Great Crested Flycatcher nestbox (entrance hole, distance from house)?

http://www.sialis.org/gcfl.htm

Great Crested Flycatcher: The GCFL usually nests in clearings and edges of mature forest, orchards, parks, swamps, and cultivated areas scattered with trees. Like bluebirds, these flycatchers are secondary cavity nesters, meaning they rely on cavities created by other creatures. They usually build their nests high up in trees (3-70 feet off the ground), but will occasionally nest in gutters, pipes and tin cans.

Their bulky nest is constructed of small twigs, leaf litter, pine needles, bark fibers, poplar/cottonwood seeds, moss, lichen, grass, and rootlets, hair (from dogs, cats, cattle, pigs, rabbits, and horses), feathers, string, seed pods, cloth and paper, pieces of onion skin, paraffined or oiled paper, bits of eggshell, pieces of horse manure . The nest is usually about 10-18" high (most are 12-15"). Off to one side (often in the back), the cup is lined with finer hair, feathers or fur. About 75% of nests may contain a small piece of shed snakeskin or cellophane.