The end on shot of the bow shows the heartwood/sapwood and gives an idea of the belly and the waggle in the far limb, which will probably be the upper one.
There is a little twist in the limbs, E.G The boundary between heart and sapwood twists as it runs down the bow. I'll allow that wist to be present in the finished bow to maintain an even thickness of heart/sapwood throughout the limbs, I'll just need to watch for any twist or sideways bend while tillering. Mind wide limbs are unlikely to bend sideways, so it's mostly twist I'll be watch out for twist.
The Traditional Bowyers Bible vol 2 has a good section on making strings, but again there is probably plenty on You tube.