Can I use Xcode with PhoneGap

PhoneGap allows you to use web technologies (CSS, JavaScript, HTML) and interface that with native features (provided by plugins). PhoneGap itself does not do any migration of existing code bases. So, if you write an app with Objective C or Swift, PhoneGap can't transmute that into Android's Java or Windows' equivalent.

Instead you'd write your app once in HTML, CSS, and JavaScript and use PhoneGap to target all your desired platforms. But that means writing the app in web technologies in the first place.

Side note: there is no other Adobe product that I know of that would do any translation of existing code either. There are some non-Adobe tools out there that can let you reuse portions of existing native code, but I have no personal experience with them.

As far as selling through iTunes, that applies only to iOS apps (not Android or Windows). Each platform has its own store.

Hope that helps.