These are the steps to follow to set up a kde environment, in more or less the order or urgency.
Can't live with that. Declare $4\times4$ in Settings then for Switching, first "Always Enabled" switching desktop on edge (0ms or minimum for everything, no animation) in Shortcuts KWin family Ctrl+(left,right,up,down).
To zoom in/out, go in Desktop Behaviour, and select Desktop Grid with shortcut Alt+E. Remove fading for both desktop & windows.
In Window Management/Window Behaviour Alt+Mouse Wheel => Raise/Lower.