Iconoscope Design and Function

[Rinehart]

I have sent the following questions to one or two people already as a private message, so please don't be offended if you're reading it again here. It's not that I am impatient or dissatisfied, but in retrospect I realize that I should have posted it here in the first place, and that's what I am doing now.
There are three main questions that I have:
1) How exactly did the Iconoscope produce its signal? My understanding is that in the original concept, (fig. 1) each cesium granule on the mosaic would act as a capacitor, the amount of charge stored being proportional to the intensity of the light shining on it. The purpose of the electron beam would be to impart energy to the granule to overcome the resistance of the insulator and discharge it to the common conductor on the other side. This method however also produced a lot of secondary emission, leading to a lot of signal noise. Later refinements (fig. 2) incorporated the secondaries into the signal by collecting them and running them through the anode ring to complete the circuit, and this somehow was linked to increased sensitivity. But if I've read the diagram right, there is a DC power source connected to the output from the anode ring on one side and through a resistor to the signal from the photoelectric element and then on to the preamplifier, so how does this return the electrons to their source?
2) I understand that Iconoscope tubes had considerable variation is the peak sensitivity of the photoelectric element across the spectrum of visible light, not only from one make and model to the next, but amongst individual tubes of the same make and model. This was caused by the manufacturing process of the scanning target being a considerably difficult one for the time and so it wasn't possible to control the outcome as well as would be desired. Therefore two different TV cameras photographing the same thing would have rendered the image in different shades of grey. Is this true, and if it is, was the difference noticeable enough that the broadcaster had to correct
for it, and how would they go about doing this?
3) Around 1940, RCA put on the market an Iconoscope tube, Model 1847, designed specifically for the amateur market. This tube featured a two-sided target, which considerably simplified things, because you wouldn't have to correct for keystone distortion. Why didn't RCA incorporate this into its professional cameras?
I suspect that I have misunderstood more than a couple of things here, and also that the answers are complicated ones. So if that is the case, could you point out some articles or reference works I could read?