first time building a kayak… where do i make my cuts on the forms so they "break away'' when necessary? below the sheer line? won't blade kurf alter the forms?

Usually when I build, the forms are left 'one piece' and the hull is stripped and glassed on the outside, then 'popped off' the forms. The hull inside is then glassed and the boat is put back on the forms for the deck to be stripped and glassed, being careful to not glue the deck to the hull. There are other sequences that different builders use -isn't it pretty clear in Nick's book? The sheer line should be marked on the plans (SH?); it's the common place to join the hull and deck.