There is a bug in After Effects CC 2014 (13.0) that causes the error that you mention. If you want to create a stereo 3D camera rig, do so in a previous version of After Effects and then open that project in After Effects CC 2014 (13.0) and carry on; the error is only in the initial creation of the rig.
Thanks for that info.
Still would love to know if AE is able to compile a side by side, top and bottom or interleave passive 3D output. And what composition settings and output settings I should expect to use.
See the settings in the 3D Glasses effect for what's available.
BTW, there's basic material about stereo 3D features in After Effects here:
Great thanks for the video and the tip. Off to play!