You gotta see if the aftermarket deck you get allows you to change the songs on your Ipod with it's controls or if you have to switch songs using the Ipod. My brother head unit, he has to change it through his Ipod, where as my friends head unit can change the songs through the head unit. I think the higher end ones will feature the ability to change songs using the deck instead of the Ipod.
Not sure about your bluetooth question.. do you want to connect your Ipod to your deck using bluetooth and then be able to switch songs using the deck? If so I don't think I've heard of a head unit able to do this yet. The bluetooth feature is usually to have your calls on your phone rerouted to your car speakers allowing hands free operation.
