I expect Wayland cinnamon will be good enough to use by next years Ubuntu LTS. And the default in the next LTS after that.
Maybe.
Not to my knowledge
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
I expect Wayland cinnamon will be good enough to use by next years Ubuntu LTS. And the default in the next LTS after that.
Maybe.
Not to my knowledge
If you got enough experience to ask this, it might me a good idea to move to a KDE-friendly distro. AFAIK, Linux Mint does not like KDE.
Cinnamon is a super simple DE for simple people. I don't mean this as an insult, some people just never even think to customize their computer and are scared by settings and options. Just use KDE if it has features you like, you clearly sound like you're up for the change.
Mint has been a very good conservative distro so I hope they continue in this fashion: transition when the rest of the ecosystem is already there so that there will be no pain for non technical users
Years.
IDK
No.
Cinnamon development is glacial. It works, but the project simply does not have the resources to properly keep up or even triage important fixes.
It's one of the reasons I didn't stick with mint, and tend not recommend it if someone can use something else. When I stopped using it, the setting that was supposed to allow games in fullscreen to display without compositing was borked, costing you frames and latency. It had been that way for years.