yes, do it the way i described above and u will be able to have the camera follow the curve and still be able to keyframe the position of the aim.
1)select your camera_aim, then press up on arrow key
2)shift selct ur curve
3)and attatch to motion path.

since u pressed up on ur arrow key and attatched the camera1_group node to motion path, this leaves heirarchy free to be keyframed.

u can always create a regula cam, and attatch it to ur curve, and create a locator, position in the middle of ur object, and do an aim constrain for locator and camera.