I normally run 17.5 stock buggy and Mod Short Course truck. Will be adding a 4WD buggy soon. For buggy I run Schumacher and for truck I run associated (because Schumacher doesn't have a truck)
The Hobby Town store carries a good selection of Losi and Associated kits and parts.
They just got a new timing system so I am not sure about all the different transponders it supports, but I do know the MyLaps hybrid (2 wire) works