Can a wired (ethernet) Mac act as a WiFi access point? A MacPro '10 running 10.6.8, connected to the network via Ethernet. 

If I'd like to add a webcam is a router required or can I set up direct access? i.e. can AirPort act as an access point?
Yes, you can do that. When Ethernet is connected, go to Sharing System  Preference Pane. You can share the Internet there by selecting Ethernet as a source.