Obj-C++ in Xcode Questions

Hi. I have been learning a little bit of C++, using books and the internet. I have sucessfully made my first program in Xcode that converts celsius to farenheit and vice versa. I learned that in order to [easily] make an actual mac osx app/game/window, Obj-C is the way to go. But, since I already know a bit of C++ and like it, I have a quick question:

How does the process go of making a Objective-C++ program (with its own window) work with Xcode? Such as:

-how to make it (I assume 'Cocoa' because I have been playing with it)

-how to code it, which file to use (and changing it to Obj-C++, etc)

-how to compile/run/make it a complete relseased app

And also, using C++ to code the actualy bulk of the program and using Obj-C to make the GUI, is a good way to go right? - and how would that work, combining two languages...?

Thanks.