How long does it take for your iphone to reboot after being jailbroken?

I know where to get iphone 3gs firmware 3.1 and want video camera on my iphone 3g. From what I have heard its just a software based camera and that's why the software update is bigger for it. So my questions are Can you put 3gs firmware on the 3g? Will it add camera? And is a software based or hardware based camera thanks for awnsering and please only respond if you have proof or can explain.

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unlock iphone 3g