Can someone explain the Touch Cards to me?

Are they similar to the Pierces in that they stay for a while? Can I only use them one time? Can I use them on more than one 4U? How much content do they have? I won't have the money to buy a 4U until January or February, will I be able to buy the touch cards then or should I buy the ones available for sale now?

I don't have a 4U myself But I believe the touch card contents are like the downloads so they stay forever, you can use them all the time you want but ONLY in 2 different 4Us (or more if they have the same username)

The only touch 4U card available for Now is the Aikatsu card, so don't woery too much, they will still be available for quite a while.

It has 2 characters, 4 items and a house remodel I believe.

The Rolatchi, Santarolatchi and Candy Paku Paku cards are not commercial cards, you get them as a gift when you buy a 4U, so if you plan on buying one in February (I plan on doing so) they will probably come with a different card (or none)