Forever! If you buy or download and app from the App Store, it will remain on your phone until you delete it. It could also get removed if you restore your iPhone. But other than that, it will last forever.
Mobilephone
free games for my iPhone
Songify might be the app your looking for.
real racing 2
No, you do not have to pay once a month to use an app on an iPhone. If the app, for example, costs $0.99, you would pay that amount and keep the app. You don't have to continue to pay that amount each month as long as you have the app.
Altough there is no radio application on the iPhone, you can download it. with the "App Store" program in the iPhone, you can download an app that gives you the opportunity for listening to radio.
There is no way to do that. If you jailbreak your iPhone there is an app on Cydia that does that.
Yes, there is an Answers App for iphone in the apple store
you can turn your ipod touch into a iphone using it.
for an iphone there's already an app called safari which is the internet
Yes, you can find your lost iPhone with an iPhone app. However, you must have access to another apple product with the same app to locate your lost iPhone. It's called FindmyiPhone in the app store, and it's free. All you do is make an account. Let's say your iPhone is lost, all you do is sign in with your account with another device with the same app and the app will do the rest. Its quite amazing.
The GoPro Quik app saves files on an iPhone in the app's internal storage.