Questions about Photon Technologies for Medium-Scale MMO game?

Hey, hope you are in excellent health.

Currently I am deciding on my MMO game's architecture, and Photon seems like it's cut out for the job.

I am thinking about using Photon (self-hosted) with Photon Fusion.

My questions are:

  1. Is it possible to use Photon Server in combination with Photon Fusion as the client?
  2. Does the default Photon Server code cater to room-based games or is it generic and will work for an MMO game?
  3. How many CCU will the server be able to handle with Fusion's Interest Management capabilities (if applicable)

I want to use Photon Fusion as it has Interest Management which is something that seems is needed.

Will greatly appreciate answers to my questions. Thanks!