Also, I am using suspend, which remembers much more than that. Works flawlessly.
I never needed a “proper” search in settings. There are not so many settings and I do not do so much customization anyway. What are you customizing?
Try Alt+F3. Using it many times a day and can’t imagine anything more convenient (not even the new Qubes menu).
Where?
Depends on your own perception of beauty I guess
Do you have examples? Default KDE would make Qubes ISO too large, which is already not small and lacks other, more important things.