Hi Christopher,
The capacity for a 201.02 chassis is 1Kg (2.2lbs) of R-12.
The auxiliary fan won't come on until the system generates enough pressure to close the switch. So simply turning the A/C on will not make the fan work. If that were the case, the fan(s) would run even when going down the expressway when they weren't needed.
As far as converting to R-134...opinions range from one extreme to the other. Officially, the rubber seals and refrigerant oil for R-12 systems are not compatible with R-134a. So, you are supposed to replace all of the O-rings and the dryer, then remove the compressor...drain the oil, flush the system...etc. A guy around here just changes the fittings and shoots 'em full of R-134a. I'm waiting to hear what happens after a few years. We'll see. The few that I've done have had everything replaced like you're supposed to (usually after a compressor melt-down). The only complaints are slightly lower efficiency at low speeds and "marginal" components leaking under the slightly higher pressures of 134a.
Regards,
Randy D.