I didn't know we could turn them off when charging. I turn mine off and they turn on automatically when I plug the charger in. Probably a setting I missed.
I don't know why anyone would turn it completely off to charge. It only has a rudimentary charging system when it is off... It's only meant to give it enough of a charge so the device can power up for a proper charge.
My iPad is always on. When it is charging it is charging at night I use it as an alarm clock. I have never charged it during the day, as thenbattery always lasts no matter how hard I try.
I do do the hard reboot where you hold power and home once a week to clear the memory though.
Never. I normally charge my iPad everyday when I sleep, and I always turn it off during those times. Though sometimes I do end up forgetting, but then it always goes off on standby mode after 5 minutes anyway.