Agree on the art, nice and clear
The avengers do traditionally have a chair yes, they even had a charter signed by the founders back in the day
I can't recall the last time a formal chair was used it's seemed to be field leaders more recent years
the chair and field leader were usually the same, though not always iirc
I think in Mighty avengers, luke was the leader but spectrum had field command, but again not a traditional set up