Official DevNet, and Prover

Hi all, been looking through the posts here, and was wondering the following:

  1. Is there an official DevNet? By that I mean a local network where I could test and improve iteratively changes to the node runtime?

  2. Where is the code for the prover used by a node? I am struggling to find the implimentation of the STARK, as well as the place where the prover is executed within a node.