Well, regarding your first question:
(1) Does a tire increase in circumference as it goes from 0 internal pressure to operating pressure?
I would say it depends on what you mean:
If you ask, whether the radius from the axle to the ground is changing with internal pressure - the answer is obviously yes, this measure is growing with increasing pressure from 0 bar to nominal or an even higher pressure.
This is by the way how modern Tire Pressure Monitoring Systems are detecting with the inverse method an air loosing wheel:
Revolution of each wheel is compared among all wheels, and if one has higher revolution it is losing air.
As you can see, the difference is significant...
Regards
Toni