Sounds like a MK2 you have there. Fuel tank should be front to back
Yes the engine should & will be a 11c
Later MK2s did have ratchet hubs
Sounds to me its had an ID or cowling change & yes it will be a 1940s machine
Sounds like oposed . If you have spark plugs each side.
Kohlers are good as long as you look after them!! Clean oil & keep on the max.
Make sure carb settings are correct & it does not over rev or they can throw con rods!!