Broken Screen Help

Hi
I have an iphone 4 which unfortunately fell flat on its back on the ground from a 1m drop. There is no visible damage (ie. screen and back plate are not cracked etc) however the screen now is white/black/blue flashing sort of. the touch screen function does still work.

One thing to note, however, is the metal frame is BENT (near the volume buttons) from a previous incident (which didnt affect the phone in any way)

I am not the original owner of this iphone (bought it online so I cant track down original owner for info on the iphone).

I have a few questions:
1. Will I be able to make an appointment with the apple genuises and how far will I get with them? I have no original documentation and Im not the original owner.
2. Can I fix this myself? Will the following link let me solve it or is it a more complex issue?
http://www.dealextreme.com/p/replac...er-w-back-cover-set-for-iphone-4-black-103722

Thanks for any insight anyone can provide