Should Space Command be another military branch or managed by the Air Force?

Managed by the Air Force.

We could wrap Army and Navy Space Commands into AFSPC (which I always thought was a good idea anyway) and they could continue to manage satellites, launch operations and the Theater Missile Defense as a branch. There is your Space Force in a nut shell. Once we get another space transport system they can roll that in as well.

It should be subordinate to the Air Force, in the same way that the Marines are subordinate to the Navy.