Firefox proxy settings on workstations

Reading the documentation about proxy settings in various applications (for example, Gajim or Electrum), I wonder about the following:

  1. When using firefox in the workstation, is it recommended to set proxy setting to a SOCKS5 at, and if so to which port?
  2. Same question, for firefox running in Windows VM configured to connect through a Whonix Gateway, as explained in Anonymize Other Operating Systems

Usual recommendation: don’t use Firefox. As per Tor Browser Essentials.

Pick any pre-configured port as per Stream Isolation