I know AA uses the E satellite and other high E gates at DFW. . . .Terminal E at DFW is used by a variety of domestic carriers — for example, United Airlines, Delta Air Lines, Frontier, JetBlue, Spirit Airlines, Breeze Airways, Alaska Airlines, and others operate flights from E gates.
Yes, but rare other than the semi-satellite CR7 gates. Dates back to the merger when they inherited old USAir gates.
Further, they are down gates due to construction of bolt-on gates in C and I think one other terminal as well.
They are sometimes used as placeholders on the advance gate assignments. Be diligent the day of flight. I've been scheduled for a few E gates this year, but all changed to somewhere else day of departure.