General Washington is considered by the Army to be the most senior general.
See https://en.wikipedia.org/wiki/General_officers_in_the_United_States
Yes, see my post:
As part of the bicentennial celebration, George Washington was, 177 years after his death, permanently made senior to all other US generals/admirals, with the title general of the armies, effective on 4 July 1976. The appointment stated he was to have “rank and precedence over all other grades of the Army, past or present.”