Connecting houses wirelessly...

I am looking into connecting my brothers house to my parents and am looking into using a homebrew cantenna. It seems fairly easy, but I had a few questions and I hope someone here can help.

First - My overall idea of how networks work is that both the router and the network cards have antennas that both send and recieve in an omnidirectional pattern. The range of each does not need to touch the other device but the wireless fields do need to overlap and the data is exchanged in the overlap of the two fields. Am I correct?

Second - Do I need one of these homemade antennas on each house or just one? My parents have the router and my brother would be connecting to it.

Third - Do these homemade cantennas need line of sight to the antenna on the other end? Or does it need its beam sent through a stronger portion of the others field?

I know that it is possible to place one on each roof and have line of sight, but it would place them far away from the router or computer. I hope this gives you enough information to help me out. Thanks.

Check out www.irishwan.ie for lots of information on building a network like this. It's a growing wireless network covering many parts of Ireland. There's quite a few similar discussions on thier forums.