The second one, yes. The first one is irrelevant.

That's also irrelevant.

I would guess that avoiding to channel too much and never as much as you could would greatly slow down or even stop the gaining of strength.

Would teachers while Accepted, or later your Ajah Head allow a sister to do that or at least not push such a sister, though? And why?

Yet all but one sister (that we know of) still reached their potential, if maybe years after gaining the shawl in some cases. I'm not saying she's a Brown or she's not a Brown, by the way.

Hope I get there before the encyclopedia...

It will probably be in it. This is something RJ could very well have included in the books, and I can see in which scene(s) this could have been used nicely. He did not use it and neither did Brandon. Nothing in the books contradicts the information, but maybe RJ changed his mind about this fact being true. I think he may just have forgotten to use it in the end. I would expect this sort of detail to be very much the type Harriet will include. That's only one small example. Many entries have interesting details like that. Some are bio facts about important characters, but a lot are little anecdotes, ideas/sketches to elaborate on if he mentioned them, often funny or colorful, that he created and assigned in advance to often minor characters. I guess he liked to have those at hand to use to flesh out minor players when they appeared in scenes rather than thinking all this stuff up before he set down to write a scene. He seemed to have done this sort of preparation a lot more in the late series, when large groups of new characters appeared. One group that really has a lot of them, of all kinds, are the Kinswomen (an hilarious one involved a woman who had been novice with Sereille "the terror" Bagand) Quite a few of them have been used in the books (incl. a lot he had devised for the BA hunters, for instance), but not quite all, so I think we have a great deal of "fun stuff" coming in the Encyclopedia.