you can purchase the license through a dealer. the license is $199.  The license gets tied to an MRX1 or MRX2.  you can add additional MRX1/2s to other rooms and they all share the same license.  You can have as many Android devices as you like.

you are correct, the app will only control the MRX1 or MRX2.

Alternatively, you could wait for the Total Control Android app to be available, then go with a Total Control system instead.  Then you use the MRX10 base station which has better processing power and more connections.