If you upload the
.dsp file then the online compiler will take care of compiling it for you (though if you change files through the Patch Edit page you probably have to manually change compilation type too). That way you can edit, compile and test the FAUST code directly in the browser
For the factory patches we always put Mix (or Dry/Wet) on parameter D, and for reverbs we have Room size on A. You're free to assign them any way you like, but it's nice to be consistent!
I'm gonna try the dirty reverb now on the OWL Pedal plugged into a Prophet 5