> The ability to expand more than one container at the same time (expand one, expand all, collapse one, collapse all, etc. )

There is already an issue for this, currently it auto collapses to make is quicker to manage. I suspect turning this off and permitting more than one to be open should be good enough right?
https://github.com/jonathanKingston/sea-containers/issues/1
Feel free to create another issue or add comments there.

> The ability to drag and move/re-order open tabs inside the same container.

This is currently possible, are you seeing issues with it?

> The ability to move/re-order the containers themselves.

This would require a change in containers itself, however it has been suggested here:
https://github.com/mozilla/testpilot-containers/issues/330