I an not sure that the story is true about Washington visiting Hoomes at "Old Mansion"; however, there is a historic marker in the front of the house which states it. Also, there were labratory tests done on the building material of the house which indicated that it was built long after the time that "legend" has it.
I am not aware of any Revolutionary involvement by Col. John Hoomes. Let me know if you find anything out. My e-mail is firstname.lastname@example.org