HOW LONG WILL IT TAKE ME TO SAVE UP FOR AN IPHONE?

I really want an iphone 4 (i know its not the newest) or iphone 4s, 4 is £319 from apple and 4s is £449. My contract ends in July (2013) and my parents won't buy me one or pay for my contract so i want to buy one myself. I'm 13 so can't really get a job so how much would i have to save a month until july?

How to check remaining data on an o2 iphone 4 contract?

I have an iphone 4 on an o2 contract, how do i check the reamining data allowance, i have unlimitied texts and don't use my minutes so they are alright and i know to text 21202 with a blank message and i get those through but i don't get my remaining data?
So how do i check my remaining data? I don't have an o2 account cos it's under my dad's name

Photo editing app for iPhone, pertaining to Instagram?

Okay, so if you know anything about Instagram, you'll know that they only give you a certain amount of space for your picture to fill up.

Well, there's some app I don't know about but I've seen other people using that allows you to edit your pictures so you can have the full photo and it'll have a white frame all around it.

Then you can save that picture from this unknown app and upload it to Instagram, I'm assuming. Then you can see the full picture and not have it cut off.

Do you know what I mean? What app is this?

How to change my credit card number on iTunes?

I have apps I've paid for on my iPhone but the last card I had got lost and there's been canceled. Is there anyway I can charge the money on my old credit card number onto my new one?