charge the battery and try again, it's an electric starter bike and so the battery needs to be in good condition and fully charged, if in doubt about the battery...get a new one
yeah a sheared key is quite common, caused by not tighnening the rotor nut to the correct spec, you'll need to get a grip of the rotor to tighten it properly
because it's a 2 stroke the transmission oil is totally sealed from the crank and piston (unlike on a 4 stroke) this means that it stays clean and has a long life, you can put just about anything in there so long as it's motorcycle oil and not car oil. some motorcycle oil will be labelled 4 stroke oil...this is fine to use in a 2 stroke transmission
as for the 2 stroke oil, yeah it's a DT and that makes it not too fussy and will be happy on cheap mineral or expensive fully sythetic, your call really, if you think about it when this bike was made all there was available at that time was mineral oil
the usual way to clean up the for sliders is to use wet/dry paper, it replicates the original 'brushed' finish (cut some strips), needs to be quite a fine grade and keep wetting it
if it only runs with choke ON then isnt the pilot jet clogged...going off what you said I wouldnt be surprised, or maybe the silicone sealant has got somewhere else?
yeh tommy i'm to kind also
mitch you seem to have bypassed the intro bit in your quest for knowlege...its not too late to redeem yersen dude
could be a number of reasons of course,damaged gasket, bolts not torqued evenly to specification, a crappy gasket (your is a genuine one I know), faces not cleaned properly before the gasket was fitted, warped cylinder head, even a cracked head.