Why do some Verizon iPhones have sim card slots?

So why is it that some verizon iphones have sim card slots and some don't? I'm talking about the visible one externally on the side of the iphone. I have seen some Verizon 4S with no sim card slot & some with a sim card slot. Why is that? Are the ones with the slot jailbroken AT&T iphones?

Alternate Ultimate Guitar App?

I want an app for my iPhone that has chords for a bunch of songs.
I was going to buy the Ultimate Guitar App but a bunch of the reviews said it's not worth it because there are a ton of necessary in-app purchases (font size, page width, etc) which make the app cost two or three times more than listed.
Anyway, I was wondering if there are any good alternates to this app. I just want to be able to have chords/TABs for songs on the go.

IPhone 4 randomly shut off, top button is broken. Am I doomed?

The top button on my iPhone 4 has been broken for a long time. Today my phone randomly shut off. Since my top button is broken, the only way I can turn my phone on is by plugging it in. I tried that earlier, but my phone did not react to that. Is there any way I can fix this without going to the apple store?

Should I get iphone 5, or Galaxy S4?

I never used smartphones before but I have iPod touch 4g. So I'm kinda used to Apple's interface and I heard that Apple has so many more Apps that are fun and better than Galaxy does.

I'm really in a crossroad between iphone 5 or galaxy S4 because they both cost $199.

What do you think it's the best?

What is the best program to jailbreak my iPhone 4 with?

I was thinking about jailbreaking my iPhone 4 I'm looking for a SAFE program that won't slow down my device. I'm completely new to this sort of think so I'm just looking for a kick in the right direction from someone who has more experience. Also if you could give me some pointers or tips that would be great.

Like I said:
iPhone 4
IOS 6.1.3