So back to the original question of WEP Vs WPA? I choose neither for my home network and decided to run completely unencrypted.... (snip)
There are currently several organizations with the goal of providing free wireless to anyone who wants it.
You may also want to take a look at LifeNet http://thelifenetwork.org/. They are developing software to build ad-hoc networks using Wi-Fi and Bluetooth on portable devices (e.g. Android smartphones) but they can also make use of wireless access points if they are available and set up correctly. In a rural area, cell phone service can be fragile, and a few well-placed access points could allow someone to route an emergency call, especially if the Wi-Fi has a battery backup. You seem to have little problem installing custom software on your router, so it may be something to play with.
In our case, we are moving to a setup somewhat similar to yours. We have a few wired systems, and internal wireless network that is severely degraded by the walls of the house (chickenwire in the old plaster in places around here). Anything important internally goes over SSL/SSH anyway. We are putting a second access point with high-gain antennas on the roof firewalled from the local network and powered off of our small solar (and soon to be wind) R/E system so it will continue to be available in a power outage such as another regional ice storm (we've had two in the last four years and one EF5 tornado nearby). We are playing with the early LifeNet software in conjunction with local Neighborhood Watch efforts. We can also use a Wi-Fi PTT app on our smartphones on or near the farm. As a side benefit, I am loading a whole bunch of documentation on a webserver which will be accessible on the long-range Wi-Fi for all that stuff people wish they had downloaded before an emergency, like how to correctly wire a generator and not fry your linemen. With a good antenna and favorable terrain, we have been making Wi-Fi connections at 8 miles or so.