Halt batch file until service stop is complete?

You can use NET stop, which is synchronous, i.e it will wait until the service stops.

See - NET stop

sc stop webdriveservice
:loop
sc query webdriveservice | find "STOPPED"
if errorlevel 1 (
  timeout 1
  goto loop
)

Another version with a repetition count limit:

sc stop webdriveservice
set count=1
set limit=10
:loop
sc query webdriveservice | find "STOPPED"
if errorlevel 1 (
  timeout 1
  set /a count += 1
  if %count% lss %limit% goto loop
)