Book: Programming with C++20 - What's your style preference?

Last week I ordered the first test print for Programming with C++20 - Concepts, Coroutines, Ranges, and more. I'm looking forward to holding it in my hands around Friday. This step means that I'm very close to finalizing this project. I took the time to look at the book, especially the two different versions, paperback, and ebook, with fresh eyes. I intend to keep the PDF ebook as close as possible to the paperback version. They should look the same. That was my plan so far. While doing some final editing, I discovered a couple of questions. I like to know your opinion too because a book is written for its readers, not the writer :-)

Page numbers in references?

My first question is for potential readers of the paperback version. We can just click a reference for the ebook and end up exactly where we need to be. With the printed edition, this is different. Currently, I list only the chapter, section, or listing number, but not the page number. So my question to you is:

Do you want page numbers along with references to chapters or sections?

What should be in the index?

A probably less easy to answer question is what should be in the index of the book? What keywords, phrases, or topics are you looking for in an index of a C++20 book?

Color or black and white?

Programming with C++20 will be a colorized book, as you can already see in the ebook edition. My question for the paperback readers is, are you interested in a black and white (or better greyish) edition of the book as well?

You can participate here: andreasfertig.com/book-feedback

Thank you for your feedback!