question 1 = No, the changer plugs are different, you would need a changer from newer model hondas/acuras with the blue rectangular plug.

As for an aftermarket deck, you can very easily add an aftermarket one... and keep your dash controls. There are adapters available that wire to the controls and can either send an IR signal to the new deck or with certain decks (new alpines, some sony) the adapter plugs right into the rear of the new deck.