Welcome!
I'm not familiar with your specific machine, but I'll try to address some of your questions. BTW, photos would be very helpful.
What part of the spindle is breaking? Is it due to poor welds? Is it a ball joint or kingpin style? There was a report of poor welds on Gio Beast ATV spindles once that I recall, but that's it.
This is my guess on the oil leak:
http://www.chinariders.net/modules.p...ewtopic&t=7678
You likely have a wet clutch, therefore a good four stroke motorcycle oil is recommended.
The drain plug on the right side is for draining. The other secures the timing chain tensioner. IDK about the fill point on your engine, but 110 engines usually have a dipstick on the right side. Without a photo, I can only guess that yours is a unit motor, meaning one crankcase and tranny, not separate units.
I used an NGK plug wire on a few of my machines. The stock wire will unscrew from the coil upon peeling back the boot.
Cheers!