Your windows look good! Yay! Probably being garage kept. They were made by SeGi and probably 90% of them fogged up.
The engine serial number won’t tell you the HP if it was changed after it left the factory.
If it WAS reprogrammed (no chip) I would change it back to prevent overheating issues at full throttle.
There is no interlock with the slides; just the ignition switch. Doesn’t have to be running just the key on but you want it running so you have max voltage at the motor.
If you have the flat floor slide, it really grunts getting it up over the hump.
Good luck and please keep us posted.