Sold an iPhone and I keep getting their messages?

Hi, I sold a sprint iPhone 4 and I think the guy activated it. I'm not sure. I did not restore it I simply deleted everything and signed out of everything. Couple weeks later I get a pop up badge that says number *** is associated with my iPhone, the one i sold, and did I want to connect it with this apple device. I said yes not knowing what it would do an shortly after I started receiving messages from numbers, numbers not saved in my phone. And it said I sent them. But I didn't. I looked at the sending and receiving addresses and the number of the guy I sold it too was listed under both to send and receive, so I just put I to receive and not send so I can still use my number and text my friends. How did this happen?

Iphone 4s or Iphone 5? I have verizon?

Memory situation: I need 32gb, I have an 8gb ipod and i have 0kb or whatever like ANYTHING left on it and i only have 600 songs and 2 pages of apps and 500 pictures, if i combined that with a phone, i'd want about 6 pages of apps total, 1000 pictures, and about 1500 songs. All that WITH about 200 contacts and my current (non-touch phone) holds about 400 texts and i delete my inbox about twice a week so that's 800 texts a week if that takes up any space? Also phone calls and such. So i think i'd need at LEAST 16gb, but preferably 32 just so i don't have to worry. I'll be around Wi-Fi most of the time so i will most likely get the lowest payment option for internet gb. The 4th has only 8gb i think and the 4s has 16gb, but the 5th has 32! So that rules out the 4th one really.

Price: free for the 4 with 8gb (can't get), $99 for the 4s with 16gb and $299 for the 5th with 32gb OR $199 for the 5th with 16gb

Details: (FROM WHAT I KNOW) Please--- give as much extra information as you can about the 2 phones!
Pros + cons for the 4s:
Pros: Cheaper, i've heard the battery life is better
Cons: Older, Siri isn't as new

Pros + cons for the 5th:
Pros: Bigger screen, newer specs and such with it that the 4s doesn't have, comes in 32gb
Cons: Battery life is supposed to be bad, the price, it's new so might have more problems?

So basically the 5th has everything the 4s has but the price and size are different, and i just can't decide. Does anyone know if the 5th comes with a warrenty so i could return it at any time, or do you pay extra for that? And will i get my money fully returned? Which phone is better? Have you had expierences with either of them? Opinions are appreciated.

**Extra question if you can, which would be a better case for the phone? Otterbox or lifeproof?

How to stop my iPhone from accessing the internet while I'm in the car?

I just got my first iPhone, and in the plan I get charged for using the internet when I'm not connected to Wi-Fi. To avoid getting billed extra, I shut off programs like facebook and snapchat while I'm in the car or whatever, but I'm still getting notifications, which must mean that my iPhone is still using the internet. How do I stop it from doing that? I don't want to pay extra.

IPhone other increases whenever i try to decrease it?

My iphone is 16GB and 5GB is full of other and i looked up EVERYWHERE how to decrease it and everything i do, makes it increase. I deleted messages, emails, cookies/history, photos and i barely have ANY apps so apps and music and pictures barely do anything when it comes to space. But i don't know what to do. Should i go to the apple store?

If I post a video on vine with my sound off will it post with no sound?

I just recorded a video for vine. After I made it I noticed my switch was on silent. (I have an iPhone 4S) so I turned it on and the video still had no sound. I checked all my settings and everything was on. All the other videos on vine had sound. So I posted it hoping maybe when it posted the sound would come on. Still no sound after it posted. Is this because I had the switch off when I was recording?