First let me apologize for not knowing much.
See this question on electronics stackexchange for more info.
The picture is the key layout. In the picture, the yellow keys are modifiers. The green keys are letters. Red keys are regular keys which change function depending on which layer key is pressed. The color printed on the key corresponds to function (the white is what will happen if no layer keys are pressed).
Would I need to use two separate matrices (one for the Layer and Mod keys, one for the rest?) Also, I’ve been using ergodox (http://ergodox.org/Default.aspx as a guide (though I cant open their pcb files). They use a Teensy, which would obviously be smaller than the arduino duo I plan to use. To save space, I was thinking of putting the arduino below the pcb, and separating them with something(to protect the duo). Is this possible? Lastly, how could I design my pcb in Fritzing if they don’t have the cherry mx brown switches? Thanks for your helP!