I know this is an ancient thread, but I thought it might keep the place tidy if relevant conversation were kept to the one place.

I have a custom ES-5V on the way. I intend on keeping everything outside of the body as much as possible to try to preserve the acoustic qualities of the top board. To that end I intend on getting a humbucker which attaches to the bottom of the neck and sort of hovers just above the face of the guitar. I'll be adding a pick guard to which I'll attempt to mount a volume and tone knob.

The only "inside" electrical bit will be the jack. I've entertained the notion of using an endpin jack if I can get a tailpiece which will accommodate (or can at least be drilled out enough to accommodate).

Would I still be looking to ground on the tailpiece if the jack is in contact with it?
Would there be any point in enclosing the underside of the pick guard where the pots are with foil or something?

...and yes, I have no idea what I'm doing!