Find my iPhone setting on iPhone 5?

So I lost my phone the other day, and I'm a total noob about all this technology stuff. If the Find My iPhone setting is enabled on the phone, does it work without the app? And how can i use that to find my phone? LOL
also. Would it work if the phone is off? I would assume the battery has died by now.

Problem if I purchase someone's Verizon iPhone 5 S still under contract?

A friend of mine has an iPhone 5 S that is still under contract with Verizon. However, it use to belong to one of his family members who recently passed away.

Questions for you Experts:

1. As the iPhone 5 S (purchased before January 2013) is an unlocked phone anyway and can use other sim cards and 3rd party pre-paid services, being still under contract, can Verizon block that phone even if another replacement sim card was used?

2. Is the complete identify and account of an existing Verizon iPhone 5 S phone found all on the sim card? If yes, I guess I can just swap the Verizon sim for a 3rd party sim.

3. My friend told me they own the phone, and they already contracted Verizon about the death in a family, but still I worry some as it's under contract yet. Maybe this does not matter?

Is there anyway to unblock an IMEI number?

Some more information:
I bought the phone off of craigslist, it is an iPhone 5S, my network is T-Mobile, and it says it's stolen when I check the IMEI number on T-Mobile's website.

Added (1). It worked for a few months until recently

Early Termination of Verizon Contract?

I'm due for an upgrade on March 11, 2014 and it's now February 18, 2014. I'm switching from an iPhone 5 to a Windows Phone, and I need to get it before I leave for a trip on March 8th. How much would the ETF be in I get the new phone this Friday? And will I be able to cancel it early at the microsoft store or will I have to be at an actual verizon store?

Is sleeping with music on bad?

I use the EarPods (the earphones that come with IPhone 5&5s) so they're not in-ear earphones and I have the music volume on Low and I usually listen to mellow music like kid cudi

Can i fill in the cracks on my iphone?

I have some minor cracking on my ipod tough 4g. I can easly type this message but reading small text can become a pain when i come to a crack. Everything works fine, but is there any way to, say, fill in the cracks or something that doesn't involve a total replacement. I just want to make it less obvious.

Will I have 4gb after my plan renews?

I'm currently on the go phone 60 dollar monthly plan with unlimited text, call, and 2gb of data. I have an iPhone 5c and i ended up using all of my data before it renews. So I added two more gb. I was wondering if they will let me keep the 4gb. I don't think two gb is enough. Ps: I don't have internet at home so I use my data a lot. But I think imma conserve it this time

My Iphone 4s is stuck in headphone mode?

The volume controls don't even show up when I have the ear phones unplugged. When I go to assistive touch, the volume controls are there, but they won't move. I can't hear any sounds when I play audio. When I plug the headphones back in it works fine. I've been using my phone lately with the head phones at the gym. Last night I downloaded a music downloader app. So any suggestions?

Added (1). It just started this a few minutes ago after I uploaded some photos to my mac pro.

Added (2). I already tried shutting it off and turning it back on with no success.