Why does my iPhone 5 battery die so fast? - 1

I have an iPhone 5. My battery lately has been dying really really fast. Over the past three or four days, it's gotten to the point of me having to charge it three times daily just to keep it from dying completely.
1 year ago, I got a new battery installed because I was eligible for a free one. Now, I'm not eligible anymore.
I would like to know why this happens, because my sister's iPhone has a normal battery life, and she's never had to replace her battery since getting the phone. We got the same phone about a week apart, and we both charge it overnight (I know it's not that good) but why is mine constantly in need of battery replacement and hers never is?

How to see what's in my iCloud?

I activated the iCloud Drive app for my iPhone but I can't see anything in it. It says in the settings it says iCloud is almost full. Must be doing something wrong.

IPhone 6 - apps not working on mobile data?

I have an iPhone 6 and recently went abroad (from UK) and I went into settings>mobile data: and under the option "use mobile data for:" I turn off every app.
Now I'm home I'm trying to turn them on but every time I switch them on and then back out to previous menu and then go back in check they are on, they re have switched themselves back off?!

Should I Face Time my cousin?

OK, I have my second cousins phone number and she is 13 and I'm a 14 year old guy. We barely see each other, we both have iPhone's. Will it be weird if I Face Time her?

How to get around authorizing step while setting up an iPhone5C?

My friend gave me her old iPhone5C a few days ago and I've been trying to set it up Example, Language>Country>Set up internet>Apple ID Authorization. I'm stuck on that last step, because the iPhone is still logged on with her Apple ID. She got a new phone awhile ago, so she doesn't use that Apple ID anymore. (I swear I didn't steal the phone or anything lol). My other friend said I can try to put it in DFU mode, (which I'm doing right now) and I can set up the phone like brand new. Its also updating to iOS 9.2 right now.