Com port leonardo

Hi,
I know there's a firmware predevelopped to communicate between atmega inside latte and .net application.
My question is : Is it serial communication ? If yes which port com is used ?
I wan't to call function inside arduino, no just send basic functions. So if I can communicate directly with serial, I do what i want.

More general, is there an electric plan from arduino inside latte panda ? Pins, com, spi etc...
Thanks