I can't even remember when I first got Fantastic Beasts and Where to Find Them, but I adored that little book. The amount of research, mythology, and sheer creativity JKR put into her universe is truly mind-boggling. My biggest hope for this upcoming film project is that Rowling is given creative freedom--- I want to see her world as she pictures it (a feeling I always missed with the HP movies).
I cast Newt Scamander a little too young here to be the author/professor/headmaster he became, but I doubt it's a stretch to say he spent much of his childhood studying the creatures in his native home. So let's go with Hogwarts-student-era Newt. I've already got a pretty nice looking beard on him in my sketchbook for when he's written his book.