One query I have is regarding some apparently contradictory information, the Xray instructions say lighter oil gives more rear traction and heavier more on power steering. Elsewhere I have seen people say heavier oil gives less rotation and calms the car down. If I find the car loose on corner entry do I go heavier or lighter?
It's not really contradictory, lighter oil gives more rear grip on power but less side bite, heavier the opposite. If you are loosing the tail on the way in a heavier oil will help because the rear will not rotate as much.
As most people have said 1k oil is probably the best starting point, depending on the grip level at your track you may find 700 is too light