How is power run to the pool house? If it branches off a circuit inside the main residence, you should look in to an Ethernet-over-power solution and go wired instead of wireless. (There are many, many options - here is one example: Linksys PLEK400 http://www.amazon.com/Linksys-Powerline-Network-Adapter-PLEK400/dp/B006J...)
Also, if you plan on playing high resolution audio through this new pool house receiver, stay away from anything that has Airplay since it downsamples 96- and 192-kHz files. It doesn't make any sense to purchase a receiver capable of up to 24-bit/192kHz if you are going to mainly use Airplay -- especially when the Airplay proprietary license adds to the cost of the AVR. Instead, get a receiver with high-rez support over its DLNA features.
P.S. Don't forget the outdoor sub!
http://www.crutchfield.com/p_107ATSUB10/Polk-Audio-Atrium-Sub10.html?tp=188