And if it is just the cashew: there is a Plasmoid on kde-look called something like "I hate the cashew" and which removes it.
You mention a lot of "I don't want..." things and all of those are not mandatory.
1. You don't need a wallpaper and by default there are no icons on the desktop. The cashew can be removed and translucency can either be switched off or you can change the theme.
2. so turn off all other effects. Plasma works fine without compositing or with compositing. It's all in one source base and we keep functionality (no reimplementation like Unity-2D or GNOME Shell fallback mode).
3. Well that is the compromise to also support users who are not as adapt with the Computer as you are. And I doubt that you configure your panel each other day ;-)
4. Right click open window -> Advanved -> Show a Lauchner for Foo when not running. For anything else as .desktop file try to just drag'n'drop it and be surprised what KDE can do :-)
5. So turn it off
6. there are so many different things referenced as multi monitor that it is hard to answer. But looking left and looking right I see that multi monitor is not broken ;-)