Number 2 is by design. Running as root is extremely dangerous, and passwordless sudo is not much better. You can, of course, allow sudo without a password by editing the /etc/sudoers file, but be concious of the security implications (any program you run would essentially have full access to everything, without you ever knowing).
Discord has a weird and confusing definition of "server". The equivalent in Matrix would be "spaces" but they are not very commonly used (and I'm not sure there is a public list). Instead Matrix is most often used with individual rooms.
Due to the distributed nature of Matrix it is actually impossible to create a complete list of public rooms. However, one probably fairly complete list can be found at https://view.matrix.org/. Most clients have room search built-in, so you would rarely need that list
But it does restrict making use of the program in specific fields of endeavor. That's the entire point of the license. I would e.g. not be able to use it in a business that sells hate speech literature.
Probably works well if you are an established company, but why would e.g. a startup pick licensing headaches over the competition? I imagine bigger companies would also rather just move to e.g. CDK or ARM if they don't need multiple providers (at least our company started discussing this today).
What kind of "custom licensing" do you anyway think a 5-person startup would get?
The biggest problem I see is that you can suddenly become non-compliant just because Hashicorp decides to release a new service (i.e.they start competing with you, rather than the other way). It can be a huge risk for companies.
For number 4, consider switching to e.g. KDE which is an alternative desktop environment you can install in Debian.
If you reinstall, consider Kubuntu, which is Ubuntu but with the KDE desktop. Search for screenshots first so you know if it is somwthing you like.