My iPhone is spazzing and i don't know what to do?

So today I put only the top part of my iPhone in the water (where the camera is) so I can take a photo, and it worked, it didn't get into any major holes and I took some really cool photos underwater. So about an hour later my phone randomly goes into sleep mode and asking to "slide to power off" like something messed up the turn off button on the top of the phone (this is a 5s) and i don't know what to do, sometimes it's not so bad but other times it shuts off every 5 seconds. Is there a way to disable the top button or am I gonna have to live with this?

Why isn't iTunes (computer) recognizing my iPhone?

I'm trying to load music from my computer onto my iPhone 6. When I try, iTunes won't recognize my device. It's not listed on the upper righthand corner. My phone asks if I trust the computer. I say yes. Then I get a message that itunes is getting an invalid response from my device. I never had this problem before.

Blacklisted IPhone 6s Plus

Here's the deal. Basically I got conned online and bought a unlocked iPhone 6s Plus that I thought was unlocked and ready to go. I buy it and take it home and it turns out that it's I was trying to buy the phone as a gift to someone close to me! So my main question is. It's blacklisted on Verizon could I use it on Virgin mobile, a prepaid service. Now, the other side to this disaster is that it's locked like I can't even get into the phone it's locked passcode wise. Do I have to just completely factory reset it? And if I plug it up to iTunes to do that will I be reported. Please someone shed some light.

Can't Open Copied Iphone Photos from Windows?

I copied iphone photos to Windows and Windows can't open the photo.

This is the error I get: The object Invoked has disconnected from its client. I have erased all the photos on the Iphone because the photos were making iphone memory not enough memory to install more apps on her Iphone.

Added (1). All the Photos are in JPG

What cell phone company would be the BEST?

To buy an Iphone 7 plus

Which would be the best for buying the iphone?

Which has the best plans?
(cheapest data, etc)

Added (1). @Marc

I mean AMERICAN cell phone companies

ie
AT&T Verizon T-Mobile Sprint