Default [Q] SIM card question

So here is my deal. I am waiting on me and my wife's nexus 4 we iPhone 5 right. My question is does any one know if I get a SIMM adaptor as my sim is a nano and needs to be micro if this will work? The other part is if the adaptor does work then I would not need to change my plan on AT&T as it is LTE and it should go down fine to HSPA+ so long as I follow the guides in setting up the apn. Anyone with information on this I thank you ahead of time.