7. I would say that yes, the SC does get to over-rule the other branches, and thwart
their will when their will is deemed to be unConstitutional - determining whether or not a law or policy transgresses Constitutional boundaries seems to one of the purposes of the USCC. But I think Scalia is exaggerating in claiming that this puts the Court at the "apex" of government, for at least two reasons: the Court has to wait for cases to come to it (it doesn't get to go hunting for things to review), and the Court doesn't get to make laws or policies on its own or order the other branches around. Plus, appointments to the Court are controlled by the other two branches, and justices can themselves be impeached (as pointed out above).
So it's not a hierarchy, but a balance of three branches with defined responsibilities.
It seems to me that Scalia is throwing a bit of a tantrum here...