You can turn most of this off using winutil:
https://github.com/ChrisTitusTech/winutil
This isn't a Windows 11 concern, this is a Microsoft Office one. You could of course block this with firewall rules, but if you are using Office365 and Microsoft's cloud products, you aren't getting around it.
This could be related to updates or #1.
I've never experienced that on any of the hardware I've installed it on
That's going to depend entirely on what the game is, whether it's running through an emulator or compatibility layer (Wine for example) and of course if it even runs. There are plenty of games that do not run or do not run reliably on Linux using compatibility software through Steam for example. Getting the game to start (often the benchmark used to say a game is "compatible" or "works") is not the same as it being able to run reliably.
That's not really an option for business environments, which is where the computers the OP is about are located. A lot of software is Microsoft-only.
I've been using Unix and its variants/off-shoots since the early 90's, even installed FreeBSD on my 486 using a boot floppy over dial-up around 1995, but there are some applications that they simply just don't work for.