1 - Between Arducopter (https://code.google.com/p/arducopter/wiki/ArduCopter?tm=6) and APM:Copter (http://copter.ardupilot.com/wiki/table-of-contents/). Which is the right place for documentation?
2 - Between DIY Drones and the Arducopter Forum (http://ardupilot.com/forum/)?
3 - Between uDrones, jDrones, and 3D Robotics?
There are dead links all over each of the sites, and as a newcomer to all of this, I'm incredibly confused as to what the go-to source is for each of these.
There is a changelog inside each release candidate version.
For version 3.0 there is a lot of changes, so it's better to wait for final version, and read the new wiki, or you would have to carefully follow the development to stay up to date.
Because of some important changes, a "quick start" manual will certainly be posted here at version 3.0 release time.
1) APM:Copter (http://copter.ardupilot.com/wiki/table-of-contents/)
is the new wiki, and eventually that will be the source if i understand correctly.
is the "old" (although still accurate for the most part) wiki, and the repository there has been shut down to my knowledge. you will notice that the "new" one @ ardupilot.com has the same, but not all of the information as the "old" one @google.com
>I am still using the wiki @google.com, but i have found that most of the info I need is on the new one @ardupilot.com also. anything i cant find at these two sources I look for here on the diydrones forum.
2) This forum, diydrones (obviously, since your reading this) has been up far longer than the ardupilot.com/forums page. it therefore has far more information contained in it. It seems like the ardupilot forum may have a more direct line to 3drobotics? (dont quote me on that)
3) 3D Robotics is the company that originally developed the ardupilot, arducopter, etc code and they were the (first) company to produce the APM boards. this project is open source, so there have been some clones show up in various markets. 3DR = the founding developers.
jDrones, to my knowledge, produced the first 'arducopter' as a ARF and RTF kit, and they still produce some kits designed around/for the APM boards.
uDrones is a subsidiary of 3D Robotics, and it looks like they sell RTF kits for the arducopter (both quad and hex) as well as the arduplanes.
lastly, the new source for all the code files is located @ https://github.com/diydrones/ardupilot/tree/master/ArduCopter BUT, unless you are trying to compile the latest release candidate (which are not fully stable releases yet), you should never need to touch any of those files.