IPhone 5 Authentication Required?

So basically, my parents bought me a iPhone 5 today on craigslist for $500 and all the persons information was on it, so i read online and they said to factory reset the phone, so I did what it said on the Apple website. Once I factory reset the phone it updated to iOS 7.0.2 and it came up to a white page that said "Hello" and it made me type in my country and language. After that it "This iPhone is linked to a Apple ID." it showed no email but @gmail.com. So I tried to type in my email and password but it said it was incorrect, so I don't know what to do, we called the guy we bought it from on craigslist and he never picks up our calls or anything. This is my first ever Apple Device, so please help me and tell me what to do to fix this and get my iPhone working.

IPhone 5s in June or iPhone 5 now?

So, they aren't going to be selling the 5 in stores after like a month, my upgrade is in June though. So my Dad said that I could either buy the regular iPhone 5 now, or wait until June to get the 5s. WHICH ONE!

Added (1). Oh, and I have the regular 4 now, not the 4s.

I bought a new iphone 5 charger and its not certified?

My white one broke so I got a new black one and it charged for a while and when I came back up stairs my phone went from 19% to 91% and now it's saying the charger isn't verified and my phone won't keep charging. I heard it's because the new ios7 update doesn't let it. How can I get the black charger to charge?

Can you buy an iPhone without internet?

I'm looking to buy an iPhone 5C but I can't afford the internet bill every month. Could you get one with just texting on it? My daughter knows someone that just has texting on it, so I wanted to confirm that this is possible. If so, how much would it cost?

Iphone5 (C) VS Samsung Galaxy S4?

I'm 16 years old and I'm looking to get my very 1st phone since I just got a job. My dad said that he would buy me any phone I wanted as long as I paid $35 a month. I really want the Samsung Galaxy S4 but when I did the yearly phone bill math it all added up to about $420 and the Samsung galaxy is only about $250 so I would be losing money by getting the Samsung. If I got the iPhone 5(c) the yearly bill would still be $420 while the iPhone 5 is about $500 so I would be gaining money which is what I want but I would much rather get the Samsung galaxy.

My question is what is you preference?
What are the pros and cons about having the Samsung galaxy and/or IPhone 5?
Why would you pick the chice you picked?

How to download itunes extras from mac?

I bought Curse of Chucky on my iphone from itunes and when it said that if i hook it up to my mac, i didn't see anywhere to download the extras. Is there a way to download them without having to buy the movie on my mac?

Is my iPhone considered unlocked?

I have an iPhone 4 (AT&T) contract ended. Does this mean my iPhone is considered unlocked? Cause I can go on wi-fi and everything. I want to sell it

Added (1). Edit: If it isn't unlocked, would people still buy it on eBay? Planning on restoring everything