It's likely that your Airport slot is fine. It's actually more closely related to the hard drive and DVD drive's bus than to ethernet.

As for surge protection: you have to protect every venue to the outside world, basically. That means that ANY item that's on the network must be protected (since surges can travel through the LAN), so that means all the power cords and AC adapters, as well as the cable or DSL line, and ideally the cable/DSL modem's LAN port too.

tooki