How were ZPMs made, charged, and are they all equivalent?

This is sort of three questions, but intimately related.

http://ift.tt/1CEpPfe and http://ift.tt/1I5oHzG

have some information, but not all reliable of referenced.

The questions are: 1) How were ZPMs fabricated by the Ancients? 2) Did they require charging or did they just spring into existence at full charge? 3) Do all ZPMs (before being used) carry the same charge?