Multiple Receivers with android remote app

I plan on purchasing three receivers for my home. My question is regarding control of multiple receivers with the android remote app.
One unit will use preamp outs for a 7.2 home theater, the line out zone 2 and 3 will also be used.
Second unit will be located only 10 ft away (next floor up) and have a 7.0 system
The third will be located 40 feet from the other two and will also have a 7.1 with zone 2 and 3.
All the receivers I had planned to be on the same network.
Do I need to set up individual wireless networks for each receiver to be able to control them individually with the app? If so how easy is it to switch between networks on the app? Or is their a choice in the app to name the receiver you want to talk to? Assuming I can talk to each one individually, I have operation questions:
When connected to a particular receiver can I adjust zone 2 or 3's volume individually and independently of the main receiver?of zone 2 to 3?
Thanks