Why is my iPhone doing this? - 2

Okay, so I've had my iPhone for About 1 year now, and it was absolutely great and amazing until recently, I dropped my phone once for the first time about three weeks ago, it was still working fine but there were cracks everywhere, nothing internal thank god. And last weekend I got it fixed, but for about 3-4 days now when I open apps, or get on FaceTime or make a call, my iPhone has been messing up, when I open apps after about, 3 hours of using my phone, like constantly, out of no where you will begin to see apps that were recently opened in the back ground of an app that is already open even if I clear my recent apps my screen is faded but still works and I can see apps or anything opened in the back ground, and when I factory restart my phone by holding the power and home button it usually works, but last night while it was restarting you could see my recent apps behind the apple logo while it was restarting! It's like a vague image of messages or FaceTime or what ever I have opened last, and IIm scared this problem could be serious! My iPhone is still usable but IIm not sure what to do!

What iPhone app would you want?

What iPhone ap would you want? I want to make my next iPad/iPhone app and I'm looking for some inspiration. What type of app do you need or maybe combination of two apps? I want to create the 'next big thing' but I need some suggestions from everyone
Thanks! : )

Added (1). Maybe a type of social network or small game

Did the update mess up my iphone battery?

I was updating my iphone to the new software up date at Dunkin and then i decided to leave without the update finished, and still haven't finished the update since i have to Wi-Fi at home and now my battery is going nuts, when i charge it it gets stuck on a number or sometimes everytime the percentage goes up
the battery shuts off and shuts back on to the new percentage. When i use it at school it shuts off like 10 times and then gets stuck on a battery percentage. I already deleted and reseted all content & settings from my phone but still no help? Do i have to buy a new battery or what by the way its an iphone 5

Where can i'm iPhone 5c for cheap?

I'm getting an iPhone but I don't want it to have a contract because I'm going to that separately and I don't want to order from Amazon or eBay etc.

AT&T iPhone 6S with 2-year contract?

Currently I own the iPhone 5S and I'm looking to upgrade it to the 6S.
The iPhone 6S with a 2-year contract is priced as $199.99. My question is, is this the price of the phone alone? What else will I be charged for at the time of purchase and in the future?