Can I use an iPhone for Sprint without a contract from Sprint?

I just bought an iPhone 5 from a friend, and their previous carrier was Sprint. First off, I don't use Sprint and second off, I don't want to buy a contract or any type of service from Sprint at the moment. So for now, it's basically like an iTouch. My question is, when i get the phone from my friend, will I be able to use it? Or do I HAVE to buy service from Sprint to get it working?

Can my data be accessed if iphone battery gets replaced?

My iphone 3gs finally stopped recharging and instead of getting the battery replaced, I want to auction it off. However, I need to know if this is a good idea because I don't want someone accessing the data that is on there. Is there a way to either take out of wipe the phone without buying a new battery?

Added (1). When I plug it in, it doesn't register on the computer because the battery is dead. "plug it in and wipe the data" is not a helpful response. What are the steps?

My iPhone 5 dies on it's own?

I sometimes go to sleep with my phone on 100% and wake up to it dead, this happens all the time it just dies on it's own I've even put it on airplane and nothing what could be wrong with it?

Can a rebel sim fix my locked to sprint iPhone 5c?

I bought an iPhone 5c off eBay which is apparently locked to sprint, a carrier from the USA. I'm considering using a rebel card to solve this but I don't understand if it will work. It says 'incoming SMS only'- what does that mean?

What is the equipment she is using called?

She is doing suspended mountain climbers( kick ***) it looks hard

I haven't see those straps at any gyms I've been to ( I'm a slacker and don't work out)
tried to google it but not getting good results ( mostly BDSM stuff)

what's it called any brand names

it's about 0:40 it to new iPhone 5s commercial

What is the equipment she is using called - 1