So, given that the “iffy” behaviour of A clears the drawing is correct, then the above list of points (actions and undo’s) is correct I would say.
In respect to your points, please note, that A causes it to create a new blank drawing. Pressing Esc will lose the floating selection (not clear the already empty drawing). Then Undo will bring the floating selection back (as you say). And Undo again will take it all back to where the drawing was a held clone.
But all my explaining doesn’t matter 🙂 The point is that you are right there’s something not right about A clearing the drawing. What I want is for both things to be able to happen (either not-clear or clear). I’ll think of a way. Aaaaanyway! 🙂