I have a strong passion for aviation and I want to pursue this passion later on in life. However, I currently want to prepare myself when that time comes. What manuals from the FAA should I go online to download and read? Additionally, which parts of the FAR/AIM should I read?
The FAR/AIM is a different beast. It’s not something I would recommend reading without context, but if you’re really that curious by all means. If you happen to have a physical copy you can find a study guide near the front. It lists the applicable regulations and chapters relevant to each rating.
If you’re looking to pursue your passion later I wouldn’t even bother with the FAR/AIM. A new one comes out yearly so why study things that may or may not be applicable till you’re ready.
I understand that there are many reasons that people wait until later in life to pursue their goals and dreams, but please keep in mind that this industry is absolutely driven by seniority and that every year that goes by without flying is one less year that you will not have at the top of the pilot food chain. If this really is your passion, I recommend getting into it as soon as possible.