[DeTomaso] ZF leak

[Lotus Esprit]

I've got a question about my ZF. I have a small leak I've traced to the plate on the bottom where the drain plug is located. I'm pretty certain the drain plug is not leaking. So I would like to take the plate off and replace the gasket. 
(1) Is it safe to take the plate off without taking the ZF out of the car. (I know, I'll need to drain the oil first).
(2) If not 1, what are the odds the gasket is okay, and maybe the bolts just need some silicone to seal them up.
 
Lastly, what's the least amount of oil/lube you can safely go before you're pushing your luck. 
 
Steve Griffin #6669