All that holds the output gear cluster in place is the flange on the outside and the c-clip you refer to on this inside. Once these are removed, it should slide out. I'm not sure the extend of the damage you did, but that may be why its not coming out freely for you.

No, you don't have to pop out the "detents" on the nut to remove it. If you have a big enough impact gun, it should just come off. I clamp the flange in a vise and hit the nut with my impact.

-Rob