Request for Resources re: pickup selection, wiring, controls, specifications (newbie)

[Hardrock ThreeFives]

Hi all, my second post;

Can anybody recommend a good resource to help me understand electric guitar pickups and specifications? I'm building a lap steel and see technical specs re: output, impedance, gain, windings, pots, &tc. Also, subjective terms regarding the sound produced by different pickups.

Thanks a heap,
-jbb