Q1. Normal / Reverse Zebra: On a bridge pickup, "Normal" is when the creme (screw) coil is towards the bridge of the guitar. "Reverse" is the other way around, so the screw coil is black and the slug coil is creme.
Q2. Spacing: If you get a ruler measure across the strings from 1st to 6th, on your Les Paul, it should be 52mm.
Q3. Conductor: 2 conductor wiring will just get you a humbucker, where 4 conductor will let you add things like coil taps / phase invert (using a switch or push/pull pot). If you get the 4 conductor wiring, you can still wire it like a 2 conductor, but if you decide to experiment later with a coil tap or phase invert, you don't have the expense of buying another pickup.
Hope that helps answer your questions.