A:Answer You only need to know, which carrier you want to go with really. Depending on the deals that are in you can get a flex plan phone and another phone free, ASSUMING that this deal still exist at the time you go to get your new phones.
Other than that you'll just need to acquire 2 new lines of service with which ever 2 devices you get.
If you don't have any phone carriers, (Sprint, Verizon wireless, AT&T) they will require you to run a credit check to see if you may or may not need a deposit.
Hope this answers you're question.