I'm actually amazed how many people comment without having a clue what they are talking about.
What you're describing is not an issue but the fix of an issue 😃
When the kernel boots with the parameter quiet, systemd should get the option systemd.show_status=auto. With this option it should only inform about failures and such like. In current releases this finally works.
To get the old behaviour you just have to add systemd.show_status=true to your kernel parameters.
Berlin, Germany: we drink water straight from the tap. It's free and delicious. If you don't feel like drinking tap, just drink a "Berliner Rohrperle". It's the same thing with a fancier name, because our tap water is awesome.
Nowadays we even have public drinking fountains dotted around the city.
Yes that's the recommended path.
Information on how to upgrade can be found in the official documentation:
https://www.debian.org/releases/stretch/amd64/release-notes/ch-upgrading.html
https://www.debian.org/releases/buster/amd64/release-notes/ch-upgrading.html
https://www.debian.org/releases/bullseye/amd64/release-notes/ch-upgrading.html
https://www.debian.org/releases/bookworm/amd64/release-notes/ch-upgrading.html
As others pointed out it might be a PITA. Depending on your installed software and configuration a new install might be easier.