Transfer files from 3G 4.2.1 to 3GS 4.3

[BigTKnight]

I have an iPhone 3G jailbroken and unlocked on 4.2.1 with 06.15 baseband and i have just purchased a 3GS and it is Jailbroken and unlocked on 4.3. with the ipad baseband also.
Can someone point me in the right dirction on how to Transfer my Files from the old 3G to my new 3GS, i have searched but haven`t even been able to find a starting off point.
The only advice i can even find that is related, tells me to "Back up in iTunes" and then restore from Backup with my new phone. Will this effect my Jailbreak? Will these files move from 3G to 3GS?? Thanks for all your help in advance

[M3th0s]

If you backup your 3G and the back it up then setup the 3GS with that backup the files should be moved to the 3GS. Your jailbreak will not be affected.

[BigTKnight]

Thank you it did work, Im glad i asked first tho

So now most of my info/data is moved from my 3G to my 3GS, now i want to prepare my 3G to sell. I would like to sell it as a working jailbroken and unlocked phone because i think i can ask for more.
How do i reset everything back to its Original state and still keep the Jailbreak/Unlock.
What is all in all the best way to prepare this phone to sell without the person potentially having access to my CC info, email, facebook, and other sensitive info? Any ideas anyone?