Are either of these Bishops bound by pronouncements the Pope makes ex cathedra? Does the Pope speak for them?
Only to a certain extent. The Pope is the senior Bishop of the Latin branch. He can make certain decisions and theological direction, as Paul did for his local bishops. They can be removed at his discretion, although, with an organization the size it is, it rarely happens. The Church, necessarily, exists in the long run and rarely does anything quickly. It is to be here until Jesus Christ returns again from Heaven, and not just until Joe Sixpack returns from the 7-11.