Before I go further - Need some major help.

The po bypassed the ammeter, black on one side of it, red on the other. Go to http://www.madelectrical.com/electricaltech/amp-gauges.shtml for more info on what the po did. This is a good site with lots of info.
Don't know about the ohmmeter part, and the bulkhead connector (the big black thing) has the wire terminated into a "hook" looking end, a small screwdriver inserted on the top or bottom (don't remember which) will push the hook in and disengage it from the bulkhead.

-Daty