Possible to use iTunes, Airport Express, and Apple Remote together?

I have:

• A large music collection in Itunes on my Mac
• A nice set of speakers in another room
• An iPhone

I know that it's possible to control iTunes on my Mac with the Apple Remote app on my iPhone (I demonstrated that to myself tonight). And I know it's possible to send audio from the Music app on my iPhone directly to an Airport Express (which I am considering purchasing).

But is it possible to control the iTunes on my Mac with the Apple Remote and send the audio to the Airport Express?

If it's possible, is it easy to switch between sending the audio to the Airport Express to the Mac with only the iPhone as a control (my Mac is connected to my TV and it's a pain to use the Magic Trackpad while in bed)?

Yes, everything you have described is possible. If you have an Airport Express or other airplay destination on your network, the remote app will allow you to select and control the output location.

As seen on http://www.apple.com/apps/remote/

Enjoy!