I think the connector you refer to is the taillight plug--does it look like this?
The harness from the lights plugs into it.
The rubber hose is a "breather" tube for the rear axle gearbox.
Re: the seat belt interlock, I have devised a "thingy" that plugs into the seat belt socket and tricks the computer into believing the seat belt is connected:
I'll send you a PM with my address, send me a SASE and I mail a couple out to you.
I have a suicide knob--wouldn't be without it:
-cliff-