Good Morning

Hope someone can help me here.

Say i wanna print a pic that is spread across 2 pages S8R collage album, do i do a single page S8R size X 2pcs (8in X 12in X 2 pages) OR it is advisable to do a combine 2 pages pics (8in X 24in) and send for printing and compile into a ablum?

And usually for such print, is it advisable to save it as Jpeg before i sent for print?

Can someone enlighten a noob here.
Thank you.