AT&T dropped straight talk, what should i do?

So AT&T dropped straight talk and walmart/straight talk has stopped selling AT&T compatible sims.
i have an AT&T iphone 4 (locked) i was wondering if there's anyway i can go through a non-contract service like straight talk?
options?

Why isn't my imessage working on my iphone 4

My imessage hasn't been working for about 5 days now. When i send a text to people who have i phones its sends as a text message. I even tried turning the imessage button one and off in the settings tab. I'm connected to a Wi-Fi as well. Can anyone help me imessage again?

Arm lenght self-shot accurate or not?

When I look in the mirror I look fine and when some1 takes a picture of me from a distance(with iphone) I look fine to but whenever I take a picture of myself at arm lenght so a selfshot I look very ugly my head becomes bigger and my nose and stuff I have read that the iPhone is NOT accurate - not at close range. It uses a wide angle lens that causes distortion when used up close (ie at arm's length).
But then why I see a lot of people on like tv and facebook take selfshots at armlenght without a problem?

So is it accurate or not

Galaxy s4 or Iphone5? Which one is better?

I'm saving up for a new phone, currently i have a lumia 710(windows phone) which is a piece of ***, everything about is just bad. I never used an andoid neither a iPhone before. Which phone should i get then?

Is it possible to transfer music from an iPhone/iPod onto iTunes?

I can't be bothered to install cd's and such all over again so I wanted to check if anyone knows whether it's possible to transfer the music directly from an iPhone or an iPod onto iTunes? I don't want to download anything for it though… I have a MacBook Pro, if that's something that has to be said, haha I'm not that good with all this technical stuff.

Can I replace the back of my iPhone 4S?

I dropped my phone a few months ago and the back screen cracked. I didn't really care about the cracks they didn't bother me and the phone worked. But today I dropped my phone an a few of the glass piece's fell out. I now have holes in the back of my phone an I can see what's behind the glass. I really don't want dirt to get in so I'd like to replace the back. Is there a way I can do this cheaply. I know I could do it myself of I could find the products. Can anyone give me any advice?

How much will iPhone plan cost?

I'm looking to get an iPhone through verizon. I currently have a basic Samsung Intensity 3 and I really want to uprgrade. I really think I only need 1 or 2 gb per month. How much would it cost to get the phone up and running?

IPhone 4S cellular data turns off on sprint?

The cellular data on my iPhone 4S (sprint) keeps turning itself off at random times when I'm away from the house. I can't figure out why. I set the data on, then a few minutes later, depending on where I'm, it's off. Even if I'm using data at the time. Any suggestions?

Where did all the space on my iPhone go?

My iPhone has 14 gigs originally and I jailbroke it. Legit the part that says "other" takes up like 11.5 gigs and i have no idea why. In iFile, there's nothing in. Trash. I have one movie on it that is 2.5 gigabytes and that's. I legit do not have that much stuff. Is all this Cydia stuff? I really have not downloaded much. I dunno why I have almost no space.