The vibration could be a bent crankshaft which would seal the fate of that mower, at least the engine. It could also be just a bent blade. The flywheel may have turned a little on the crankshaft, shearing the soft Woodruff key there for that purpose, and advancing the spark. This could account for the engine speed. The smoke may be engine oil that got into the intake tract and muffler if you picked up the wrong side of the mower to check it out. I wouldn't run it until checking out these possibilities.