Their firmware is not special. About the only thing it does that is special at the moment is talk to their screen. There are firmwares out there that are designed to be used with multi function machines like RepRapFirmware (https://github.com/dc42/RepRapFirmware). RRF is neat because all configuration is done through Gcode. You do not need to recompile to change any settings. It also supports macros for things like tool changes, homing, pausing, etc. Those macros can change any setting so you can have one acceleration for 3D printing, one for the Laser, one for the CNC.
As for dual extruders, the print volume of the 3-in-1 is not really big enough for dual extruders. Dual extruders require an offset in X which will eat from the print volume. Instead of being 120x120x120 it will probably be more like 80x120x120. Which is kind of on the small side. A better solution would be to use a mixing print head like the E3D Cyclops.