Fabric softener is great for pony hair in general - it is nylon hair after all so something that looks after fabric is better than something that looks after real hair.
BAB hair, as you know, can be more than a bit wild and fly away so the key is to allow the pony as little play time as possible (or keep her hair in pleats).
As for their bodies a surface wash with a sponge in the best bet and allow to air dry.