A:AnswerThere is a button (looks like a power on button) on the top side (connector side), which you press and directly opposite there are tiny, blue LED lights. Four lights on = fully charged. Thus unit holds a charge for a long time.
A:AnswerYes; I am able to do pass-through charging but, of course, the unit doesn't get fully recharged until you remove whatever it's charging; it stays at pretty much the level it was at when you initiated the daisy chain charging until then; depends on what it's charging.
A:AnswerIt has a new-standard USB in-out port and a micro port for charging. Plug a USB cable into the unit, then into a charging head, not supplied, that's plugged into an outlet; or use the micro port with an appropriate cable, supplied.
A:AnswerNot if they use the older-style, trapaziodal-shaped USB; the built-ins are only for the new, oval-style USB. It has internal monitoring to prevent overcharging, so it claims.
