1) ArduPilot Mega (that's the hardware). ArduCopter 2 (that's the software)
2) No. Not sure what you mean by hit or miss, but what part of the wiki are you having trouble with?
There's a Glossary of Confusing Terms right on the front page of the site.
That cleared things a bit ! I seemed to have got confused looking at the docs when they link from one area to another. I'm just trying to get the whole project straight in my mind how it all works together
The APM & AC2 I was referring to came from the config part of the mission planning software - APM Planning.
Looking at it again I think I've got the idea of the APM2.X hardware PID's and AC2 software settings.
Good catch. We'll clarify the nomenclature in the next software rev.
Could you let me know if Wfly WFT07 2.4Ghz TX/RX is a good choice for ArduCopter?