Fair use: Instructor sharing notes from textbooks
I think you mostly are in the clear from an ethical/plagiarism perspective. Making your own notes off of a course textbook is perfectly acceptable as long as you appropriately reference the textbook. You can write a broad attribution in the beginning: these notes are largely based on the material in chapter X of textbook A. If you’re planning to take questions from a book but not more it’s fine to just reference the book for any specific questions you took from there, and list it as additional material.