yes, but not all iPhone 4 apps are available on the iphone 3gs/3g/2g becuase they are too high resolution apps, or need a front facing camera.
No, the iPhone 4 is not the only iPhone that will work with Verizon. All iPhone models, including the iPhone 3G, 3GS, 4, 4S, and 5, will work with Verizon.
no why do you think its called trading in?
IF you have a computer and have installed itunes on it (no duh you wouldn't have apps with out i tunes:P) all your apps, videos and songs SHOULD be saved on i tunes so just sync the iphone 4 2 itunes and there you have it. :)
iOS 5 will be compatible with iPhone 3GS as well as iPhone 4.
Yes, they should be able to. The iPhone is backward compatible. Yes, they can. I used to have an iPhone 3GS and all the games work on my iPhone 4.
Yes, you can put an iPhone camera in an iPhone 3GS provided you have the required skills.
iPhone 3GS. Then the iPhone 4 and then the iPhone 4S.
Probably not, it could work vice versa, but a #GS is too thick to fit in most iPhone 4 cases.
yes
yes , uu can .
No. The only iPhone that has the ability to FaceTime is the iPhone 4.
iPhone 4 ,however my father has the iPhone 3GS which is quite good.