You can see bits of the metal coolant pipe in a couple of the pics. One where it's coming out from behind the cat - the O2 sensor and it's wires are in the foreground - and then again another bit of it sticking out from behind the oil filter. It's looking quite "crusty" and I think a closer look is advisable. Becky's was a bit weird in that it actually looked pretty good with good paint for most of it's surface. I decided to dismantle it because it was leaking from the rubber seal where it plugs into the back of the water pump. Initially I was just going to renew the seal but after I removed it I found some deep rust pits around where the bracket is welded on and in one other place. As these pipes are a known weakness I decided to just renew the pipe itself. Whilst I was going to the bother of removing the old one anyway. By the way getting the pipe in and out behind the exhaust is tricky and needs a little thinking about how you need to twist and turn it but it's doable, just, without removing the exhaust itself. (I did have the heat shield loose at the time because I was repairing it's fixings which had fatigue fractured which probably made the fitting of the pipe a little easier. By the way it's simply a push fit into the back of the water pump. I lubed it with some silicon grease and even then it needed a very strong push to get it in place. A good clue as to whether you've got it fully pushed home is to check whether the hole in the securing bracket lines up with the tapped hole in the block. Be just a little careful with that securing bolt when you remove it. Felicity's (1992 Panda parade) sheared off in the block which was quite a pain but the others I've done all came out just fine (being on the front of the block they tend to rust a bit.)
The last pic posted shows the inner driveshaft joint quite clearly and it looks nice and dry, no sign of oil. On this evidence my bets would be on the cam cover gasket being the culprit.