The fax number in given the first post is just fine, and make sure you mark it for the attention of the room assignment team. Quote your full booking details, and give them contact information (email for example) in case they need to get back to you. See
http://www.portorleans.org/room-requests.php#Requests.
Personally I'd suggest explaining all of the above in a fax, as you've covered it pretty well there.
I think it's more useful to explain what you want from your room location, and allow them to work something suitable out for you, rather than second-guessing the allocation team by asking for one specific location - which if they can't arrange, leaves them wondering what the next-best option might be.
Oak Manor is certainly a good choice in general, but the very end of Parterre Place (nearest the bridge) is also excellent, and it's very close to the pool tool, so don't rule that out.
Andre