before you get too concerned make sure that white smoke is not condensation in the exhaust pipe. If your exhaust is wet (inside) before you start up in the morning it wil look like white smoke. Just look or feel in the tail pipe before your next startup.
The shuddering may indicate a problem, or it could just be some air in the fuel system or other fuel related problem (the typical cause of surging/stuttering). That knob i the bottom of filter is used to drain any water out of the filter. Usually you open for a second and you would drain any water out of filter but if there is more than a cap full of water you would want do a though evaluation of fuel system (ie does tank need to be drained?).
I’m sure Dave can provide more insight into what to look at or check.
Good Luck