What's this?
Why is there a pool of oil under the car from this?
And what can I do to stop said pool of oil?

Sorry about the quality, the only camera I have is on the phone. The Silver object on the right is the exhaust heat shield.

thats your oil pressure sender unit. Dunno why it would be leaking, is it loose?

thats your oil pressure sender unit. Dunno why it would be leaking, is it loose?
Due to it's close proximity to the exhaust and radiator, I've not really been able to test it for looseness.

sometimes they just start to leak around the pressed join on the outside. o've seen then blow the centre out completely and then run the sump dry.

Check your camshaft to waterpump oil seal.
and clean and check your pcv and breather.
definanlty dont overlook the oil switch that could blow a hole in your radiator

sometimes they just start to leak around the pressed join on the outside. o've seen then blow the centre out completely and then run the sump dry.
Yep. It fixed, but required the car to be towed. (Oil refused to stay there, and I wasn't gonna risk it.)