Tindrrel - as for placing the bridge - check out DB's instructions in the How to Build Your PitBull Guitar thread (http://www.buildyourownguitar.com.au...ead.php?t=3048). It's with a P Bass, but the process is the same for pretty much all hardtail style bridges. Only difference that I've found is drill your neck screws and put two opposite screws in so that they are still a little proud (easier to get out), but hold the neck solidly - that way you don't need to work around the quickgrip.
As for the resistance difference between the pups - depends on brand - Entwistle Jazz Bass pups .3 k diff, SD Soapbars 1K diff, SD Jazz pups .2K.
Other thing to look for is the length of wire - if they're both pretty much the same, longer wire neck pup as it will give you more room to move.