bmaeser

no, but redundant

samba / smb if your clients are windows/macos

nfs if your clients are linux

with any of those, you dont even need media streamling like plex, you can just use plain old kodi on your devices and add the shares to it

i have been using fastmail for about a year now, never had any issues with smtp delays or mails not showing up in 'sent'

i also use protonmail. for smtp (or any 3rd party client) you need to upgrade your account and install the bridge. this is because you need something to handle pgp.

check out retroarch

and/or retropie if you run it on a raspberry pi