Is it possible to use an IPhone 4 (Verizon) for AT&T?

I'm with Verizon and I have an iPhone 4 (that is no longer in use--I upgraded to the 5) and my friend (who is with AT&T) desperately needs a phone.
I heard I can call Verizon and ask them to unlock (I forgot the word for it) --to where the AT&T SIM card could be used. But where would the sim cars go?

Is it worth buying the 4s or the 5?

I'm getting am iphone this week and i was thinking the iphone 5 however some say that there's hardly any difference between the 4s and 5.So should i get the 4s or just go with the 5 unless you can tell me all the differences between the two to see if its worth it. Also which colour is better and typically more preffered and why?

Are there any free messaging apps that don't need Wi-Fi?

I'm going away in a few days and the place I'm staying has no Wi-Fi. But I've got to try and keep in contact with my best friend because she's reviving some news this week and she wants to tell it to me when she hears. I have an iPad and she has an iPhone, and she doesn't have any credit so we can't text. Are there any free messaging apps in the app store that require no Wi-Fi!

What are some activities to do without using technology?

I have a friend who has concussion syndrome and gets headaches. She went to a doctor and the doctor either recommended being in a completely dark room for extended period of time or get rid of technology (screens - like tv, computer, phone). She can't read either. She can have something read to her though.

Now all she does is play board and card games all day and listen to books on tape. She can use siri on her iPhone, but it's probably not the best to listen for awhile. She can't really exercise because she got her concussion from playing sports. She can't go shopping or be in a place that's loud or a lot of lights. Because that's too much stimulation.

I thought of two things she can do: 1.cooking/baking 2.arts and crafts (painting/drawing)

Can you guys think of anything else that's good that wouldn't stimulate headaches like that?

Should I take my iphone 5 to Leeds fest?

I'm totally torn yes I know it's a risk but I will have it with me 24/7 and It'll be on a wrist strap so I won't drop it I just really need something to take good photos with and I figured my phone would be the best option.

Is iMessage free internationally? - 1

I would like to iMessage my friend who currently lives in Canada and I live in the new york in the US. We both have iphones so we both have iMessage. Will it cost money to imessage back and forth because we live in different countries?