The Midlands raceway setup looks a little odd BUT so is both their surface and how tight the track is (more suited to 14th scale than 10th really).

Why 25deg castor, it's all about getting the nose in to compete with the likes of the KF2. Once the car is turned in maintaining steering through and out of the corner is all about roll centre tuning.

For the wet I normally drop the inside of the rear link to 1 or even 0 under ball stud, move rear shocks in 1 hole and raise the whole car a mm or 2. If it's really slippery then go to zero antisquat to manage sidebite.