I think you said most of what you need to say but it's confusing the way you worded it. It takes a minimum of two rappels to get down from the top of zig zag. A 60m rope will not reach from the top of the second pitch to the chain anchors at the top of the first pitch. Rappel to the snag, then rappel of the madrone tree either to the chain anchors at the top of the first pitch, or to the bottom (I think a 60m rope will make it to the ground).
From the top of the route, if you have one 60m rope, do this:
One rap to the snag ledge(top of P.2)
One Rap to the big tall dead tree(rappeler's right)
One rap to the ground, barely makes it.