Some of this needs a dose of common sense...
Shocking Grasp, Arc Lightning and other electrical effects vs. metal armour, for example - the armour should give a penalty, not a bonus!
If you want to invoke RL physics, metal armor will provide excellent protection against electrical attacks by grounding them. Same theory as a lightning rod.
Touch AC (and surprised AC) are easy enough things to keep in the game; and touch AC will be needed later on anyway unless incorporeal creatures are gone.
If heavy armor is to be an actual class advantage, then it should be universally applicable.