Why does my iphone 4 flicker?

My iphone 4 flickers randomly every now and then but when it does it goes absolutely nuts.
I slide the lock and then it flickers and goes back to the lock screen and then it goes to the thing where you slide to turn it off… And you have to press cancel then it flickers back to lock screen etc etc it repeats. It gets really bad at times but then my phone is normal…
Why is it doing that? Should I get it fixed how much would it cost roughly?
(AUS)

How to run, search and use iPhone apps on my mac OS?

I don't really have an iPhone nor an iPod touch but I want to download some stuff that seems it "can't " be run on my mac. So how can I get an emulator were I can search for any kind of apps and use them as if I were on an iPhone/ipod?

How to hack the shore app?

Does anyone know how to hack the shore app on iPhone/iPod/iPad?

The shore is a chatting app and has in app purchase that I would like to get for free

While trying to delete data off iPhone 4s?

The lock button on my iPhone 4s (that I've had for less than a year) broke, so I went to the Apple store to get it fixed. They said I could get a new iPhone for free, which is great. But, they couldn't give it to me yet because not all of my info was backed up on iCloud. Evidently, I didn't have enough space to back it up.
The nice worker told me to delete at least 4 GB of pictures (I had 10 GB worth of pics.whoops) so I did that. I deleted over 2, 000 pics off my phone and kept them on my iPhoto, which gave me a lot more storage room.
BUT, now I'm trying to sync my phone normally and it says on my iTunes, "Adding 1, 750 pictures to iPhone… "! Because now I think my computer is trying to add all these pics to my photo library on my phone. The GB just keep rising now, thanks to my computer trying to re-sync the photos.ugh.
Sorry if this is confusing, I'm not the best with technology but I usually know what to do.
Do I just never let my phone sync the pictures with my computer?