Well dude i dont suggest you go with one mobile, alto the 3G connection may be smart thing to do, i dont suggest to having 5 accounts on one phone, that is a BIG RED FLAG for facebook and your accounts will probably get banned/asked for firend verification every week/or ask for phone verification. Although i think you will be ok by handling only 3 accounts on one phone but you will have to maek sure when you finished using one account you wait around 2-3 hours to start using the other (this way it will look much more real to facebook, as if someone gave the phone to someone else to just login and check facebook, as normal people do)