You dont go anywhere in game. You turn your DS on with AC:WW in the slot and then go to the main DS menu and select download play. The game will download the moving van application to your DS and then it transfers your character and catalogue. No tools/money/items/etc. Just its appearance and name.
If you have a flashcard it won't work, at all, for any of them.
The suitcase is for visiting other towns, you download your character from the wii to your DS in a similar way and then when you get to a friends house you transfer it across to their wii to visit their town etc (I think).