You shouldn't be blowing gear oil through the vent. It shouldn't be leaking from the top cover gasket either.
You might want to either drain & refill the tranny or pull the top cover (only 8 bolts, easy to get to with your floor access panel removed. I say this because your tranny may have taken in water, especially if the jeep has sat without a top and you have a tear in your shift boot. Mine was like that and it was way overfull; looked like a banana milk shake in there (fluid was yellow and foamy).
If and when you pull the transmission top cover, it should look something like this (minus the yellow gunk you see here):
While the cover is off, throw another gasket on there unless the old one is in good shape still.