Redman,
I am just an amatuer myself but I will share what I've learned so far.
Looks you are making laminated bows and I have zero experience with that. But when making selfbows I use a 4 inch handle and 2 inch fades. On a selfbow, any longer than that is waste, especially on a shorter bow, because you are taking away wood from the limbs that could be working to fling the arrow. As far as handle thickness goes, you have to leave the handle thick enough to not be working (for a stiff handled bow of course). My standard thickness is 1 1/2 inches. But if you were doing a lighter weight bow you might get away with a slightly thinner grip but I haven't experimented with that.
And you ain't hijackin'. Discussion is good.