Since there seems to bee no fuel tap, the probable best way to drain the fuel before replacing the line would be just to pull the line off and drain it into a big coffee tin or glass jar until the tank is empty.
Its very possible that the oil being overfilled will make it smokey, I have seen this case more than once
As for the slow starting, I would imagine either your starter motor or battery is tired, it could even be the earths/ connections to the starter are dirty.
