Alnbren, I got the idea for those tips from some Comanche arrows shown in the picture below.
(A full size illustration of one of the arrows is also in Jim Hamm's Encyclopedia of Bows, Arrows, and Quivers, Vol 2)
I do not harden the wood unless it is hickory. The arrows I made are birch.
I cut them the same way by eye....one at a time. After I carve the first arrow point, I use it as a guide for the others.
I do the nocks the tapering the same way. The tapering is a bit tricky because I have to make sure the arrow spines match and also keep tabs on the final weight. I have to start with dowels that are matched very closely in spine and weight before they are carved. In all, they take about an hour each to make.