Looking for a consistent answer about battery calibration
There are slightly different opinions around on this topic. To fully understand the issue, one needs to first understand how LiIo batteries work (which goes a little too far for our site, so please read details on Wikipedia).


Lie Ryan is absolutely right: LiIo batteries don't take it well to be fully discharged.
It shouldn't be done too often. I'm not sure what a double-take should improve here.
Usually there's no need to do that "explicitly". If you think of how often you end up with an empty batterie (as it doesn't last long enough), calibration is already done as a side-effect (if you then fully charge). It's widely agreed that it should not be done more often than once in 60..90 days, so Logas might have mistaken the term.
See previous point :) I never saw reason to calibrate any of my devices' battery, though.
It certainly cannot hurt to do it with the device turned off, as then it's not being charged and discharged at the same time. I doubt it's really necessary, but it does no harm :)