Ya, the early ones started by the flywheel. And you had to open the decompression valves like you said.
But to let that GD magneto get ahold of you..MAN! Just about the time you could get away it would nail you again.
NEVER...mess around by the spark plugs when its running. EVER.
Yes, on the magneto and plugs. Low enough current, but the extremely high voltage and relatively slow cycles can put the hurt on a man for sure.