Can I unlock an iPhone with any carrier?

Hey I'm trying to buy an iPhone off craigslist! I want to use it on virgin mobile but some say AT&T or Verizon etc. So am I able
E to use it on virgin mobile!

What does this mean on data plan?

So I just got the iPhone 5, and I wanted to see if how many data I had used. On my old phone I had already used 117 out of 200.So I dialed the data thing and it said this:
Next Bill Cycle: 01/21/13
Data (MB): 62.66 of 200
Data (MB): 200 of 200 (Deactivated)
Messaging: 8, 828
Group Messaging: 9, 881 of Unlimited
Visit us online at www.att.com/DataPlan

This was just a few min ago. What does deactivated mean?

I found an iPhone at a restaurant?

How do I return it to it's rightful owner? The phone is locked and requires a password to unlock. What do I do?

Added (1). Funny, Ben, but no. These phones are expensive and if I lost my phone, I'd want whoever finds it to return it too.

Added (2). I'm bringing it to the Apple Store tomorrow morning.

Added (3). Everything is good now, the owner called the phone and I answered. He's on his way to pick it up.

Added (4). Thank you all for your help.

Can I lower My Current Iphone Data plan to a Cheaper One?

I'm on the share plan, only one I could choose. With I got unlimited everything except data, so I picked the 4gb thinking I would use a lot of it, I notice I hardly use that much at all. So is there anyway I can lower to the 2gb without disrupting anything on the contract? If I can change it, will it effect getting the down payment back when I pay a full year without missing any payments? Also If I can change it, How do I go about doing it? Can I do it on computer(preferred way) or does it HAVE to be by phone?

Got a new iPhone 4S that does not support flash?

I can't watch any videos that require flash, for example videos on fb friends uploaded and the iPhone doesn't support flash. Is there any app I can download that can substitute adobe flash or maybe an alternative version I can download?

IPhone: 3 bars of Wi-Fi but no connection?

3G works perfectly but Wi-Fi has always been faster. Now out of the blue whenever i connect to my router it doesn't connect to anything, yet there are 3 Wi-Fi bars.tried forgetting network, tried whatever i could think of.

Why do I look better in pictures than in the mirror?

Ok so I feel like I look better in pictures on my iphone Front camera than in the mirror or if I take a picture outside and on the pictures I look nothing like how I looked in the mirror. If that makes any sense, but I feel like I look different and better in pictures hows that possible? Which one is more accurate? I been feeling so ugly lately cuz i don't know if I look how I look in the mirror or my iphone front camera pictures. Ppl have told me I was pretty but i don't know which they see? It really depresses me, I don't know how I even lookk. Please answer, thanks in advance!