Nunua HiPhone. Much better. Comes with two sims as well.
For credit you probably have some applications running in the background - like locations. So either disable them or disable mobile data and or 3G. Or let them run but buy a good data bundle which should give you a virtually unlimited mobile data.
Bluetooth- good luck with that. iPhones are notorious for not pairing well with other devices. Read someone that they primary purpose of the bluetooth is to use with accessories like hands free and not to communicate with other devices. Don't know how true it is.
PDF, Word etc from PC to phone - use iTunes.
He who can express in words the ardour of his love, has but little love to express. - Petrach, Son. (That men by various ways arrive at the same end. - Montaigne, The Essays of.)