You are probbaly having trouble finding clear information because the areas are full of grey.
1. Fonts : require commercial use permission and in cases of single fonts require the purchase of a commercial license. Though there are some from free fonts made avaialable for commercial use the majority need purchase under comercial terms. So in order to use the fonts you must ennsure that the terms permit commercial use.
2.Photos - yes photos taken by a client are theirs to do with what they will. The use of commercial photography requires a release by the photographer and each will have their own opinion about what credit is required. Some require just a footnote but some require the credit be given on the actual photo itself.
3.Elements: Each purchase will come with a TOU and you need to respect the usuage rights in the TOU - some permit use, some dont, and some require that they be contacted individually for permission.
4. ""Do I just add a page at the end of a bound book or with the layout pages that makes note of Fonts, Elements, etc? How do I do this?"" Personally i think this is the best choice
5. Ensure that you follow TOU - if in doubt either dont use it or contact the deisgner for clarification.
HTH