Help starting out with getting some dark themes

Hello, longtime Start8-11 user, testing out windowblinds 11. 

I use a program called REAPER and it's fairly skinnable, but on windows there are elements which cannot be so easily skinned, and they stick out like sore thumbs.

I found one way to make a theme for windows that is darker, but it's strange, over time it reverts. 

Finding a way to make things nice and dark is what I need. My questions:

1. What dark skin themes are available which have a modern win11 look? I have Fl8t i think, but it's a bit ...flat. hah. Basically, I just want this, but otherwise a kind of typical dark mode win11 theme:

https://forum.cockos.com/showthread.php?t=228668&highlight=dark+theme

"penumbra" theme for windows seems to do it but it gradually reverts overtime.. I dont know why? 

2. Can I remove this more boxy look around the taskbar icons? 

3. Will this damage my system in any way? It's strange but I remember messing around with themes in the past and actually not even being able to boot windows! This seems like a very different paradigm and program so I find that unlikely, but I figured I would ask.

4. Skinstudio looks at least somewhat user friendly! Does this edit just about every part of a windows look? Or are there limitations? Does it come with windowblinds? 

5. Is there a performance hit with windowblinds?