#1
So here's the thing.

I bought these EMG's second hand, they appear to be the new solderless system which is part of the problem,

Here's what I have:

EMG 81/85
Battery Cradle
Bridge Pick-up Cable
Neck Pick-up Cable

I'm missing the Pick-up/Battery Buss, 25K Pots and Stereo Jack output.
I can get hold of the Pots and the Output Jack, the problem is finding a way around the Buss.

One last note, the passive Pick-ups currently on my Guitar are coil tapped, will I need to replace the 5 Way toggle switch installed and replace it with a three way?
#2
If you use the 81 (or 85, whichever your bridge pickup is) almost exclusively and having two dead spots on your 5-way switch doesn't bother you then you probably don't need a 3 way switch although bear in mind this may or may not bother you in the near future especially should you decide to switch between the neck and bridge pickup (or both) more often and you play at a live setting.

As for the buss well...best try to contact EMG or the local EMG retailer at your location and ask if you can order the buss separately. If you can still get a hold of the guy who sold you the EMGs and ask him for the EMG buss then do so.
#3
you can buy the kit with the bus and all the wiring from the EMG website, i bought a second hand set as well and went through the same thing.

i went for a 3 way switch with mine, worth spending the extra 10 bucks to make it so that it works 'properly'
Terrible guitar player.