Q: If a trade element has wagons and goats, does it still get it’s +10 movement bonus?
A: If the wagons are pulled (as opposed to carried by elephants) then the +10 is added to 18 instead of 27 since an element pulling wagons moves at walking speed instead of mounted speed.
The only way you can gain full benefit from the Trade Element’s movement bonus is to either not carry wagons, or haul them empty atop elephants. I would only do the latter if I were delivering empty wagons to another unit, or hauling them across swamp or LCM hexes.
Q: Can a Trade Element (besides Trade) do anything else besides Hunting and Herding when they are moving around hexes?
A: They only hunt and herd. But they can also be assigned to defending themselves.