What will happen if I reset my cellular useage?

I have an iPhone 5 and I don't have a lot of storage left, so I went into settings and deleted some apps, but that barely did anything. There was something that said cellular usage and I clicked on it and it told me I have like 2 GB of received messages. First of all, does this have anything to do with my problem, and second, if I hit the button that says "reset statistics" what will happen?

Is my iPhone 5 battery fine?

I'm just curious about my iPhone's battery life. Is it doing well? Here's my usage stats:

Time since last full charge:

Usage: 4 hours, 30 minutes
Standby: 1 day

Current battery percentage: 43%

Added (1). My iPhone's OS is iOS 6.1.2

Why is my iPhone camera blurry after jailbreak?

I have and iPhone 5 iOS 6.1.2 and I used the evasion jailbreak, the other camera is perfect but when I want to take pictures with the front camera it looks real blurry. Would I have to take the jailbreak off?

How much does an iPhone cost in the USA? - 1

I'm Italian and people here in Italy think that in the USA all is cheaper. In Italy, without a contract an iPhone costs 729, 829, 929 € according to the memory (16, 32, 64 GB). And know that an usual salary is 1000 €.

I plugged my iphone into the computer and it erased everything?

I plugged my iPhone 4G in because it did the cord to plug into itunes and it said "Restore IPhone" so i clicked that and then it REPROGRAMMED my whole phone into my younger sisters ipod settings! All HER contacts and information is now on my phone! HOW DO I GET MY STUFF BACK!