Parent page range changes

I'm setting a longish (400+ pages) book, with 5 parts and 30+ chapters. I'll have running headers with part titles on verso pages, chapter titles recto.

Q1. For the sake of simplicity, assume I've got a parent page per chapter. What happens when the page range of the chapter changes (due to layout changes, say, or additions or deletions to the text, or what not)? I'm assuming that the parent page remains assigned to the "old" page range, and has to be redefined or reassigned, but I wonder if I'm missing something? (I'm thinking of Word or Pages, where each chapter might be a section, and the section carries header/footer material. I'm new to InDesign, and near as I can tell I can't associate a parent page/spread with a section per se.

Q2. My chapters start on recto pages, and should not have a running headers. If the corresponding verso pages has text from the previous chapter, it should have a part title in the header, but if it's blank I'd prefer that it not have a header. Am I in for a lot of manual work? 

I get the distinct impression that book layout is something of an afterthought in InDesign.