You should be able to work out where the oil is coming from fairly easily, the clutch should be ok... i had a hole in my gearbox casing recently which dumped oil all over the clutch, i cleaned it down with some solvent cleaner (or brake cleaner) and altho it slipped for the first 100ish miles it's been fine ever since, i've also been told washing up liquid and water mixed is good for cleaning oil from clutches.
Unfortunately there is a couple of common faults with the Diff on O2J box's that often cause punctured casings, first is the final drive gear rivets failing (these can be replaced with ARP bolts), and the other is the roll pin which holds the Cross Shaft which the spider gears run on in place shears, causing the cross shaft to be able to move... puncturing the box... (spider gears and cross shafts can also fail, but not that common on the variant of the o2j fitted to most 1.8T engines, which have better quality diff gears and a thicker cross shaft).
Best thing is to get the box off and investigate.