Fundamental Degrees of Freedom

What are the fundamental degrees of freedom of String Theory? It is not exactly clear!
The high energy string scattering seems to put a bound on the smallest scale one can resolve in string theory! What if one pumps more energy?
Is there a link with Hagedorn phase transition? If yes, what is the new phase? A topological change in space-time?
Is there a link with the end of a black hole's life?
Isn't it fascinating?