I'll chime in with the common wisdom -- if you feel good about your guy, and can afford to have the work done, do it now while you're already prepped. You won't want to go through a second iteration of clearing the room and living with the rumpus. And as mentioned, this could be a good time to upgrade your insulation if it turns out that that taking out the planks means going down to the studs anyway.

While you should know whether his estimate includes painting, it probably doesn't. Painting is simple enough that any nominally able-bodied person can do it themselves, though.