Autopsies are done by county MEs, who find the medical cause of death.
There is no such thing as a Federal Medical Examiner, though an outside pathologist could be brought in to review the results.
Yes.
But we all ready are aware of that.
The issue here is to examine claims made based upon prior examinations that Terri Schinlder was abused. That becomes a criminal issue.
The point being to not overlook this. It will happen just as you state, i.e. only the immediate cause of death will be looked at and if there are any physical effects indicating ealier abuse, those will not be examined and no conclusion could be come to one way or the other.