Getting adhesive off walls
That depends on what you consider easier. If the project budget is up to it(if it's easier to spend than take time), tear-out and drywall would be less labor intensive most likely. But if you don't mind getting a little dirty, taking your time, AND if the damage isn't too terribly bad, you could probably get the glue off and repair the plaster. You could always try a spot and see what happens, if it doesn't look right when your done, you're only out your time and could always tear-out and drywall later.
(quote)But if you don't mind getting a little dirty(end quote)
I didn't mean to imply that tearing out and re-rocking wouldn't be dirty, if you're going to tear out, make sure you seal all the doors as well as you possibly can, close and seal all vents, registers, returns, etc.. If the floor is staying, cover it WELL. Try to find an exit for your plaster out a window maybe, directly out if at all possible, not through the house. Drop cloths outside this room, to walk on during breaks, etc. Don't forget about the pictures on the opposite side of this wall, if you start pounding out plaster, it's almost a sure thing they'll fall.
One other alternative would be to rock over the plaster, but I wouldn't do this myself. It's difficult to find studs to screw to(as opposed to slats) and even if you do, it takes longer screws(which isn't a big issue, I know), but I'd rather take the time now to remove it than find problems later on. Also, this gives you a chance to update wiring, plumbing, etc inside the wall.