#2
Its when u take a humbucker and take a push pull volume control and make it sound like a single coil.
#3
Humbuckers are two single coils, wired in a way that cancels the hum you can get, hence the name (they are slightly out of phase)

Coil taps are just when you only use one of the humbuckers coils, so its really just a single coil pickup as your wiring it like that. Commonly yes, push-pull pots are used for it but it doesnt have to be
Gibson 58 RI VOS Custombuckers
Mesa Lonestar Special 2x12
#4
Congratulations on both getting it wrong.

A coil split is when you use just one coil of a humbucker.

A coil tap is a reduction of the output on a single coil pickup. The final effect varies slightly depending on how the pickup was made, but that's it in simple terms.
Yes, I know everything. No, I can't play worth a damn.
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