Hi
It might be worth joining the Facebook page as you will get more answers quicker these days.
https://www.facebook.com/ukshortcourse/
As for rules we are just waiting on them to be uploaded to the BRCA site but you can run any 540 size motor from the brca list in 2wd with 2s Lipo again from the brca batteries list. If you are running 4wd then either 540/550 motors are allowed (550 motors don’t have to be on the list but 540 must).
Truck wise in 2wd most run associated, TLR or PR with a few Xray conversions also appearing over the winter. 4wd most run teckno or TLR
Hope this helps 👍