I think you're right about #2 - that one was puzzling me as well, but it does look like it's meant to take the place of a follower.. the long angled skinny bit sitting on the bottom of the magazine, and a little stubby "shelf" to hold one round up top for the camera.
#1 I'm fairly sure is a mount for the rear sight -- you see how it has two little ears? I think the round parts sits flat on the rear or the frame, and those two little ears stick up and to the rear -- then the barrel of the rear sight is mounted through 'em.
I.. um.. think. :confused