Who was Washington's estate manager at Mt. Vernon in 1792?

Answer 1

In 1792, it was Anthony Whiting, according to the excerpt I'm citing below.

The bill of materials George Washington prepared in 1792 and sent to Anthony Whiting, his estate manager, serves as the primary source of information on the wood used. In the list, Washington specifies that certain pieces were to be purchased from Alexandria merchants, while others were to be obtained by Mount Vernon workmen from the plantation. Since the treading floor was to withstand the weight and punishment of trotting horses, durable white oak was his choice. Most of the remainder of the wood for the barn, except the cypress roof and the ground floor interior octagon posts, was of pine. Washington omitted the ground floor posts from the original list, possibly because he was contemplating using brick piers instead. The wood for the original was acquired from Mount Vernon, and because it was procured locally, we felt justified in using oak.
http://www.mountvernon.org/visit/plan/index.cfm/pid/594/