It is possible to have in the HD, backups of my ps3 gameS?, I mean...I own a GTA 4 game and i want to copy it in the ps3 HD for fast accesing without needing the disc? I find myself this disc very sensitive to touch and scratch!.
In short nope. Blu-Ray discs are more resilent to scratches than a normal DVD they have an additional protective layer.
Yes and no. You cannot copy the WHOLE game over, but the developer will set what they want to install to have faster access times. You would be hurting for space if you could copy the whole disk trust me.