Hello.
Yes, it is possible to have more than two Wixels talk to each other; we have some Wixel apps that support that (e.g. I/O Repeater). These apps can be found under the “Wixel App” section of the Wixel user’s guide along with their descriptions. (Please note that the Wireless Serial app and other apps based on the radio_link library only work in pairs.) One of our forum members also wrote his own app that communicates between more than two Wixels. He posted a link to his tabletop project, which uses multiple Wixels with 3pis to navigate through a grid, as well as a link to the source code in this forum thread.
As for your second question, you could have up to 128 pairs in the same area with each pair on a different radio channel.
- Amanda