Ok I don't know how the friend thing really works, I had 1 friend that I could visit their world so let me look about it and I'll let you know, I know it has some thing to do with ppl you have traded with on your actual game, I'll let you know!!
Ok you can't take berries with you, and when you find one there you need to plant them in the garden to make more, also where did you read about a promo thingy for walmart?? I have never heard of an event from there at all!!