How reliable is buying something off Craigslist?

I got a crack in my iPhone and I found the cheapest deal on another iPhone on Craigslist. Person said that the phone is basically brand new. They just need the money for something else. I'm wondering how reliable buying something off Craigslist is? I've never bought anything off Craigslist so how do you usually pay for items?

Minecraft pe local area multiplayer problem?

So i have ipad 2 and iphone 4s and both have full minecraft same versions
i used to play yesterday the day before but today iphone can no longer even locate server on ipad an other way around
though strangely they can both connect to friends galaxy s3 server (same version) visibility switch is om

If I update my iPhone will it unjailbreak it without any problems?

I'm having to use my sisters old iPhone (4s) and it needs to be updated so that I can get on instagram and other apps successfully. If I update it will it mess it up? Do I have to have a computer? Also let me note that it doesn't matter if I lose anything (or everything)

What is going to be on the iPhone 6?

So apple is suppose to be coming out with an iPhone 5s and an iPhone 6. I think I want the iPhone 6 because I have a metro Pcs samsung galaxy and I hate it, I had it for two years I want to upgrade lol. I'm going to have to buy it on my own because my dad said hes not going to buy me another phone so I have plenty of time to save up. But my question is what is going to be on the iPhone 5s and the iPhone 6? I'm 15 years old just so you know.

Online Shopping Safety

Is online shopping safe? It's like my father's friend ordered two apple IPhone and what he actually got in his delivery was two apples! That was kinda funny and I started laughing but he was sad! But I now scared to do online shopping! Have you ever done online shopping? Do you think its safe? Can you list some websites you have shopped from like amazon etc? Any bad experience with you related to online shopping.

My Wi-Fi is not working! Details?

My Wi-Fi was working fine. I run with century link with a modem with a router packed with it. (So its only one box). I was on my android tablet and i was messing around with my Wi-Fi settings, and what i did was i changed my Wi-Fi to static, then put in some random numbers for the DNS1.

After that, my Wi-Fi does not work on ANY of my mobile devices. (android tablet, iPad mini, iPhone) It works fine on my computer, and i haven't checked my ps3.

I have unplugged my Wi-Fi and plugged it back in, still no results

Do any of you have any suggestions of what this might be? Thank you.

Added (1). Now on my ipad, the ip address keeps changing, and all of them are different than the one that is on my computer which i think is the right one.

Also, instead of my subnet maask being 255.255.255.0 its 255.255.0.0

Added (2). It also may be that my pc and ps3 still work because they have a wired connection.

How do i enter the proper information? WHat i did to fix it was go to static, enter all the correct information, then back to DHCP. I still can't connect. And my iPad is displaying the wrong information still.

Added (3). How do i go to automatic? The only automatic i see is HTTP Proxy, then it tells me to enter a URL. How do i switch it to automatic? And my Wi-Fi is now working on my phone, and i did not even bother to touch it.

Added (4). I know nothing about this stuff, I don't want to change anything, I just want my Wi-Fi to be the same.