RecoStudio MultiCam supports up to four cameras (four video sources). If you are using the built-in camera on your main switching device, then you can connect up to three other external cameras via WiFi.
If you disconnect the built-in camera on the main switching device, the you can connect up to four additional external cameras. You can also choose which camera is used as the audio source.
Screencasting is possible using a Mac by installing "Switcher Cast" from your Mac's App Store.