I would ask you for some specific photos from you of you or the person you would like to be the subject of the origin story. These would be photos of the person in profile, straight on, close ups, etc, so I would have enough reference to get his or her face as close as possible.
Those photos could still be candid, however, so if the origin story is a surprise gift for someone else you wouldn't blow your cover by having to ask for an impromptu modeling session.
Additionally, I'd ask you what were the most important characteristics to try and nail down throughout the comic, then hop into work.
It won't be universally silent, no. Gracie might not be much for talking sometimes, but there will be regular dialogue as we introduce more characters. So far, I haven't felt like it's fit the mood to have much dialogue.
I love color, and it's a huge aspect of most of my work. For this, however, the black and white allows me to play with the lights and shadows of a circus in really fun ways. I think it suits the intended mood of Circus Saudade, too: Intimate, mysterious, and a little spooky.
That said, there's obviously color in the prints and I bet I'll do some special panels that are colored.
Don't see the answer to your question? Ask the project creator directly.