Ok, here's the story.  I've taken out the muffler and cat. converter.  
The O2 sensor is really stuck in the converter. so,

1)If I use heat to get it out, will it damage the sensor?

2)Should I replace the sensor anyway since it's probably original?

3)Is it nec. to have a working sensor for the engine to run well?

4)Is it nec. to have a working sensor to pass emissions tests?

5)Finally, since I've had my '87 (few weeks), I've noticed that only the 
large plug coming out of the O2 sensor is connected....the little plug 
was just hanging loose.  Someone told me that this means that the O2 
sensor wasn't really hooked up anyway.

I'd like to put my exhaust back together, so any help soon would be 
appreciated.  New sensors are very expensive, so I'd like to avoid it if 
it's not necessary.  By the way, any preferred method for taking off the 
old flange gaskets?  Is a putty knife just fine?

Thanks,
david