IPhone :: When Delete A Photo From 4s And Sync It Up To The Pc It Would Just Delete The Photo From The Computer?

it deletes all my photos. I have since then began to import my photos to my Computer.However, after restoring again, i realized when I sync my photos to my iPhone they are in a seperate folder called Photo Library? Why? I don't like how I can't just sync the camera roll to the PC. (E.G When I delete a photo from my phone and then sync it up to the PC it would just delete the photo from the comp, and if I add a photo it would add the photo to my specific folder, therefore keeping a synchronicity) Is there absolutely anyway to fix this, i dislike having the seperate folders, thing is.. I can't even add the photo library to the camera roll. I understand the camera roll is for photos taken by the camera, however I add many wallpapers through apps, why can't I add my photos like that to the camera roll and delete the unnecessary folder?

Info:
iPhone 4S, iOS 5.1.1, NOT JAILBROKEN!