Does anyone know whether you will be able to connect with friends even if they have wild world or city folk? I really hope so. None of my friends who I connect with now are going to get Jump Out and I still want to see them and their towns.
You're not going to be able to. You'll have to use the other version of the game to go to their town.
There are many conflicting things that will prevent you from going from the 3DS to the other ones, most notably all the new features, not to mention Nintendo not allowing it.