Wow, sounds frustrating and to be honest i dont have a proper answer, though i did have a similar problem so might be able to help a snippit of your question
I had that noise with my grinder as if the burrs were touching once per revolution when they were really close (about 3 clicks above the actual touching point). Ive been told that this is because the burrs arent perfectly parallel (as you said) and that it is not actually the cutting bits of the burrs touching but another part of the aparatus, so the sound is not actually the burrs grinding themselves away (phew). So now im often grinding on the setting a few clicks above the touching point and i find i have to to get a good extraction time. If i turn the empty grinder on at this setting i can hear this noise (and hear it slow down as the RPM slows after releasing the grind button). Strangely this disappears if you wiggle the hopper thing. And its not audible if there are actually beans in the grinder. You may have read the thread where that was discussed. The link to the video is http://www.youtube.com/watch?v=UMhbXh6s8X8
In answer to your last question (well, im not sure how to answer it really but i hope this isnt totally useless!); my rocky seems to grind fine enough for my silvia but i generally only use settings "2" and "3" (above point "0" which I adjusted for). I did think this was odd and asked some people if there was something wrong with my rocky but I dont actually know.
When i first heard this faint whirro f the burrs touching i thougt that this was the point "0" that everyone talked about but it seems that that was point "3" or so and if I clicked it down lower (with the machine unplugged and moving the burr by hand) I found the "0" point when the actual burrs touched.
Maybe what you described as the faint whirr of the burrs touching at attribute to point zero is actually a few clicks above zero and is a result of that non-parallelness, so maybe you are grinding on say, setting "5" or something and can actually grind a bit finer??? Does that make sense?
Hope that helps