Re: adding electric start
You can get a kit from your local J/E dealer, 173344, for about $700. Comes with starter, starter bracket, new flywheel, start switch, wiring, neutral switch, rectifier and stator for charging the battery.
I guess it can also be done with a starter, bracket, flywheel, start switch (really big one - no solenoid), and associated wiring as a minimum. I think I can find the mfr. of the start switch if you get that far.
Might be worth just selling your 9.9 and picking up one with electric start.