MY apologies, I didn't pay enough attention to the version, the attached file is now v18, unfortunately I only have 64 bit version of AL installed so I can't run an animation in v18, but it should hopefully work (saved back to v18 after testing in v19).
1). The reference point that AL uses is the standard ref point (x,y,z) of any object, irrespective of any operation like transform which is carried out, this is normally the centre of extents when an object is created, in the file I used the seke (keyboard shortcut) 'D' to pick up and put the reference point into the centre of the circle before re-recording the key frames.
2). Sorry - see new file attached to this post.
3). Yes, AnimationLab takes no notice of any transformation points, and uses the objects own reference point whether single or group ref point.
Once you get used to moving the reference point to the point of rotation before recording keyframe you shouldn't have any problem rotating anything, there is one quirk, in that if the reference point is moved after a keyframe is recorded, then whilst the recording will use the new ref point of the object/group, it will move this point and the object to the coordinates of the pre-recorded point, this is because the keyframe editor records the x,y,z of the reference point at that moment in time, so if the reference point is subsequently moved, AL will shift the position of the object/group so that the new ref point will be at the exact x,y,z coordinates it has recorded.
One needs to re-record the keyframes if the reference point is moved, this only applies to keyframe editor, commands work differently, sorry if I make it sound complicated, its not really.