What network iPhone should I get?

I'm looking on US ebay for an iPhone to use here in Ireland. What network would be best to get, what network can be unlocked here in Ireland and used here with my o2 sim card?

What is a reasonable price to pawn an iPhone 4 s?

It is about a year old.
Very good-perfect condition. (no scratches or cracks and works perfect)
Only used it for 3 months until I got a different phone and plan.
Looking for the best and most reasonable price to pawn it and get it back later.

Added (1). It has been jail-broken, but not unlocked yet. It's a Verizon phone.

Otterbox armor or incipio atlas?

I have an iphone 5 and I'm looking at the incipio atlas and the otterbox armor case. The price is not an issue I know the incipios screen does not work underwater but does the otterboxs screen function under? I have a life proof and I don't like it. So which one do I get

How to bring my whatsapp alerts back?

Whenever anyone sends me a whatsapp message I only revive it when I actually open the app, so how can I bring the alerts back even when the app isn't opened? Btw I have an IPhone 5, thanks

Should I put a screen protector on my iphone 5?

I take good care of my iphone 5 and I always have a case on it but I don't have a screen protector. I thought it was supposed to be scratch proof but I've noticed tiny scratches on my screen… I feel like screen protectors don't show the good HD quality of the iphone though…

Is there any image that can only be seen through iphone camera?

I don't know if i can be able to ask this in an understandable way, but I'll give it a shot. I need a QR code that looks normal when you look at it but when you look it through your iphone camera, it'll be seen different. Is that possible? If it is, how can i do it or to get it from someone or somewhere?