Migrating from Sonos, purpose built PC questions

I am considering migrating from Sonos Connects. I have sixteen zones in my house. Lots of questions:

  1. I would like to build a PC, stuff it with multichannel sound cards and have each output or pair of outputs be a zone. So a 7.1 sound card might provide at least four zones.

  2. can I apply a REW generated EQ curve to each speaker?

  3. is there a pager interrupt function so I can have my doorbell trigger an mp3 of my choosing and then go back to plying whatever it was?