Short Summary: The Fusion Process of the Sun

The fusion process inside of a stellar object is a controlled process.
It is the heavy elements present in the core of the stellar mass that mimics the control rods in a fission reactor.
Spectrum analysis only allows for an elemental breakdown of the materials burning near the surface due to gravitational compression within the core.

Questions to Ask?

Why does a fission reaction need controls rods for a contained reaction rate and fusion does not?
In a supernova, the core of the star has access to large amounts of fusion material at once. How is this different from the mankind's concept?
Once a fusion reaction is initiated, what controls or stops it?
Is the gravitational force created by the Sun's mass sufficient to contain the outward expansion due to the fusion process?