If you want to know about technique then the best place would be with Salzedo’s own pedagogical works.
Modern Study for the Harp
Method for the Harp
The ABC of Harp Playing
The Art of Modulation
Any of these will give you an understanding of Salzedo’s approach to playing.
If you want to learn more about Salzedo himself Dewy Owens wrote an excellent biography, From Aeolian to Thunder: A Biography of Carlos Salzedo.
As for recordings I recommend Salzedo himself. There is a set of CDs from various live radio performances he has done, including Theme and Variations. It also has some excellent interviews with him, as well as some later interviews with various people who knew him. It is called Salzedo On The Air.
If anyone can comment directly on the piece itself it is probably Saul. Hopefully he will come along soon.