1. Is it better to hook the cable/dsl modem to the airport base and then connect the base to a wired router or the other way around.
- Broadband modem --> Wired Router --> AirPort Base
This gives you the most flexibility, but you have to set the base station correctly: uncheck the "distribute IP addresses" box on the Network tab of the AirPort Admin Utility.
2. Do I need a special cable to hook the base adn router up?
- No. Any ethernet patch cable should work fine.
3. If the router is a wirless one will it effect the airport extreme base's wireless signal?
- Yes and no. If you put both of them close to each other, you can have problems (but why would you?). It's best to keep them far apart (you can go 100meters with ethernet!) to prevent such problems and help extend your wireless network.
4. Are there any special setup steps to have the airport express boost a airport extreme base station?
- Can't help you with this...