I’ve not experienced the first issue, so I don’t have a great deal of input for that. Could be a display specific behaviour.
For 2, I’ve had the Steam UI hang on occasion, though this has not occurred recently. I’ll try to see if I can get this to repro again.
For 3, there’s a few things worth bearing in mind here. AMDGPU and the Windows Radeon KMD don’t really have a lot on common. I’d be interested in any perf comparisons you have between the two systems even with the default mclk on linux. I find that Fedora is more performant in somewhat surprising scenarios, like with CP2077, Halo Infinite.
For 4, I could show you how to leverage the powerplay sysfs interface and run this via systemd service at login if you’d like?
Unfortunately have no input on 5 as I use Firefox but I hope you find a solution.