so i have a 3g and i am getting the new iphone when it comes out. i want to keep my current iphone just as a ipod touch basically. i just wanna keep the tomtom app on it and music and keep it in my truck. can i sync both of the phones thru my itunes and share the apps back an fourth and will i be able to keep upadating the apps on my 3g even though it not longer has service? thank you.