Well it has been fun today, but will not be able to keep the lead indefinitely so someone else will need to step in eventually.
Can't say on the gas grade, we haven't got into dynamic compression yet- another lesson for later
I'd start with premium, get it running good, then try mid-grade. Not so sure about regular but might be OK.
Glad to hear you already have good instructions on setting the timing. If the engine is running then no real reason to put it off. The last time I had a "newbie's" car in my garage for a checkout the timing was way, way, way retarded. So far off that I was afraid to advance it all the way to 36 deg without test driving it half-way there. Made a huge difference in the way the engine ran.
Not sure what to say about the carb- not exactly a light topic for someone new to them. Other than the idle does it seem to work OK? FYI pulling the choke closes the choke flap and also increases the idle speed by raising the throttle position using detents on the choke assembly. Pushing the knob back in opens the choke flap but the idle speed does not reset until you step on the gas a bit. So the engine speed increases. Perfectly normal.
The plugs may clean up when you go for a drive with everything set right. Cold idling does not do them much good.