Process: Creating two pages for a book on a 24x12 inch document is far easier than trying to get two 12x12 pages to match. I share some thoughts in a post, The Gutter Between Two Pages, The Gutter Between Two Pages.
Love the outfit. Especially those glasses! Your extraction is amazing. Great job on the double page layout, too. It really is different from the two pages designed separately.
wonderful photos and love the progression of the butterfly it took me a while to master this, but I too now work with double page spreads, first running an action to set up all borders and margins. Since I don't do 'lay flat' printing, I lose quite a bit of the gutter, but still design to span it.