I personally use ASA’s books for exam prep, I prefer to have a physical book, and I do the practice exams online and ASA prepware will give you a sign off to take the written.
However, I do not think that ASA prepware gives you all of the questions, rather they provide you with most of them. You can only take 5 free practice exams with each ASA book purchased. I passed the exams but there were a number of questions that I have never seen before, my scores were in the 80-90 range, I’m ok with that but for those who want higher, you may want to consider Sheppard Air. Other pilots told me they would get in the high 90s or even 100 on their written and they said they saw every question before while studying.
You also need a plotter and E6B, pencil / eraser. You really don’t need anything else, you want to learn how to fly and it’s already a lot of work. Great to have the PHAK and FAR/AIM but I doubt you would use it at the early stages. I finally bought a FAR/AIM book almost a year after getting my instrument rating, now that the beginner stuff is becoming more second nature, I can focus on commercial and other items.