One thing I noticed in the WebGUI was that it supports some kind of wireless feature. If I have a PCI Wireless NIC, does that mean I can configure monowall to be a wireless access point as well?
Yes, if you have a supported card. If you're running 1.2x, the supported cards are very minimal, and 802.11b only. If you run 1.3x beta there are a lot more options.