How do I disable receiving calls and messages?
There are several ways to accomplish this:


Airplane mode: You say that it doesn't allow GPS, but it does. You need to enable GPS when you're in airplane mode. 
Disable radio: In dialer enter *#*#4636#*#*
Select phone info and pick turn off radio. 
Take out your SIM card. This one is only applicable if you have a GSM device.
You can enable call forwarding in Phone settings -&gt; Call forwarding.


If your only problem is that calls interrupt music than you can try using a music player allows you to set how audio focus changes are handled. One example is Poweramp.