theres too many info liao.
Try google for it. You be able to find sites with plenty info on what make humbucker a humbucker while single coil a single coil
Along the way you will find extra infos on splitting the humbucker, combining the pickup wiring in series, parallel, in phase outta phase etc
After that, try searching for active pickup/passive pickup in the box at google. There will be another more pages of sites with info on whats a passive setup, active setup, whats the advantage/disadvantage, why passive, why active etc...