Yay, Christine! Board books are so fun!
I agree with all that's been said by Vijaya, Karen, and Debbie. Like Karen, I suggest putting illustration instructions in brackets [italics, too, just to make them stand out even more]. And while my board book experience has been with an educational publisher, I do know of other houses who accept unsolicited subs (Blue Manatee Press first comes to mind).
Best wishes!!!