Assuming they haven't gone non-stock, I'd get the valve cover gaskets from a dealer. There are several online discount suppliers online, like
www.orderinfinitiparts.com www.infinitipartsusa.com etc. If it's a small order, sometimes it's cheaper to order off of ebay... shipping costs for small orders from the online suppliers are high for small orders.
I think there's a few fins on the metal P/S pipe as it crosses behind the front bumper. I'm not sure that anyone has seen a need for a p/s cooler, especially with frequent (I do it every oil change) partial fluid changes.