you cant go wrong following Sam's b-along. I shot several of his bows, including a R/d Ipe. It shot so well, i was amazed. it was very consistent with glass bow performance, and Sam makes his tips so light there was hardly any handshock.
I have followed his site on my Ipe bows, and although i still feel like a beginner most of the time they are coming along.
1/8" for the bamboo over the handle and tapered to 1/16th at the tips. Be careful when sanding the rind, to not knick it or go into the power fibers
hickory i have always glued on at 1/8", i did parallel, but my next one i will taper also and it will probably work better