Assuming your questions aren’t rhetorical…
Plex is having some issues with their plex.direct DNS servers. This would affect a client application’s ability to find your server and potentially cause login issues. There was also a problem yesterday evening with the auth servers.
This is very subjective. I don’t find the UI difficult to navigate, personally. What do you find problematic?
Again, this is pretty subjective. I personally have enjoyed some of the ad supported movies.
This setting was removed due to security concerns. It was described in more detail in some post which eludes me (it may have been the server release notes).
Edit: Yes, I was thinking of the Plex Media Server release notes for 1.19.3.2793:
