The boost fluctuation Could be a faulty actuator, the smoke could be the valve stem seals yes they went on my fiesta but it's a bit weird y yours seems to do it when the engine is hotter than normal (after a bit of abuse) then goes back to not smoking when driven normally. When the valve stem seals go they tend to leak oil when engine is cold because the rubber goes hard and gets softer with the heat, not 100% sure so wait and see if anyone with a bit more knowledge on that can tell you a bit more lol could even be your piston rings see try a compression test,
Also try and note how much oil you go through after say 200 miles