I am considering Ubuntu Server 18.04.2 LTS for a personal home server. Though, reading online about things like Zeitgeist and Unity Dash (Online Search Results) I became a bit concerned about privacy. As far as I understood, mentioned "tracking" features are included only in Ubuntu Desktop (not in Server version), nevertheless I am wondering:
The answer is no to your question. All the things you list are related to the desktop and are not related to the server edition.
There is one service connected to Canonical on a server. The service responsible for crash reports is apport. You can stop it with ...
sudo service apport stop
or just purge it
sudo apt purge apport
If so, how do I disable/uninstall those features?
The desktop has a "settings" where you can disable external communication and can set up relations with external provides (google mail and drive, amazon and others). All if them are opt-in.
I don't get your paranoia though.
If you are afraid of governments spying on you there is nothing you can do about that. They do that at the ISP itself.
The information shared with Canonical is not retraceable to you and is used to create user statistics pages. How else do we convince people Ubuntu is the best :)