Should I upgrade my iPhone 4 to iOS 7.1.2?

I haven't upgraded my iphone to the new version. I was wondering if it was worth it. I don't like the look of the old version, but I've read that if you upgrade it, it will make your phone slow? Is this true? Should I upgrade it? Are there any benefits if I upgrade it?

IPhone 7.1 update must connect to iTunes?

I have an iPhone 5. Recently, I tried to update it to the 7.1.2 update. When I started updating it, it turned off and said I needed to connect to iTunes. I did as said, did a hard reset, and everything seemed to be going correctly. But afterwards, it did the same thing, except now it just needs to factory reset. I've been plugging my phone into my computer, and it recognizes sometimes. But when I put it into reset mode or whatever, it says it isn't recognized.

I do not have the original Apple charger that came with the phone. The charger worked fine before the update thing, so I know it is NOT the charger.

Does AT&T allow jailbreaking?

I want to know if AT&T will care if my iPhone is jailbroken or not. Will they do anything if they find out it is? I have not unlocked the device or anything that affects the cellular use of it; I have only installed themes, and other customization tools. If anyone could tell me if they would care, I'd appreciate it.

Are there voice editing apps for iPhone?

Are there any apps that can make my singing voice sound better or good? I'm not horrible at singing, but I'm not really good enough to sing in front of people. Also, is there a way to add music (like guitar or piano) to it or do I just play that while I'm recording? And I'm willing to pay a little bit for it.

Thanks!

Added (1). I don't need to add fancy effects like fading in and stuff like that I just want my voice to actually sound alright

Added (2). I don't need to add fancy effects like fading in and stuff like that I just want my voice to actually sound alright

How to update iPhone without itunes?

I wanted to update my phone but I didn't know I needed iTunes so started to update it and now it says I need to plug in my phone but iTunes isn't working right now. I don't know what to do. I can't do anything on my phone right now and I need too.

Does apple take screenshots when the home button is pressed?

A lawyer was telling a group of us at a seminar that each time the home button is pressed on an apple it take a screenshot and upload it to there memory. Kinda how google saves each search each person does. But the lawyer said that the first thing she would ask for in a case if they had am iphone was to see the pictures that were uploaded from pressing the home button.