Daisy chaining routers together will cause you headaches. Multiple NAT's tend to break

of things on the Internet unless you REALLY know what you are doing.
One SOHO router per home. Get a Wireless Bridge if you want extended wireless signal. Linksys makes a couple good ones, one of them even has a 5 port switch built into it. That will save you the headache of running CAT5 through the house.
Use MAC filtering AND WEP if you live in a populated area, MAC filtering alone is probably sufficient if you live in the sticks (risk profile, yada yada). All you will really do is deter the random oppurtunity seeking, non criminal, net leeches anyway with nothing but SOHO gear.