Reading material should include ISO 9001:2015, ISO 9000:2015 and, if possible, ISO 19011, latest Edition.
One of the challenges is for you to "think as an auditor". Too many people attending such courses can't make the mental transition from implementer to auditor.
It depends. I did quite few implementations of various standards over the years and my methodology was to make a plan and audit the results prior to registrar involvement. Then again, my first lead auditor course was back around 1994 so I did get auditing training.
As to the original poster - What to expect:
1. Four long days of work. Fifth day is about 1/2 day.
2. Evenings of work.
3. As Sidney posted, have the appropriate standards in your hands. My preference is paper copies, but I was raised on paper and I like to be able to mark up paper copies.
4. Be ready to actually "be" an auditor, as well as to be audited. It's part of the "game". Off hand I can only remember a few of the "tricks" they play (too long to write about here), but be ready for "unusual" situations. This is where some people fail because - Well, there is a certain amount of "personality" involved. E.g.: Some people are more easily "fooled" or "tricked" than others. A strong personality is sometimes very important.
When auditing, be aware of "tricks" as simple as "time consuming diversions" by auditees, especially upper management. Time management in auditing is very important.
The "tricks" and such that the course instructors play are for the better - They are intended to replicate real world experience. The instructors in the better courses have been around for a while and know the tricks auditees play.
Remember that many people who take lead auditor courses are really not ready (qualified) because:
1. They lack experience, and/or
2. They do not fully understand the standards the course is about. Having a copy of the applicable standards does not mean the person actually
understands the standard(s) (sentence by sentence, paragraph by paragraph) and how they are inter-related.
Suggestions:
Get enough sleep and don't "over-medicate" in the mornings by drinking a lot of coffee.
Take time to think things through - Don't rush to conclusions or act in haste.
Maybe because they ARE implementers, and someone told them this is the course to go to for all things "ISO"...?
Not unusual. That is essentially why I did my first one back in 1994. No one told me to, I wanted a better understanding of auditing which I did not have a significant background in at the time - It helped me a lot. I highly recommend lead auditor courses to anyone implementing a standard. One can not, in my opinion, effectively implement a standard which one can not audit effectively.
Best of luck, Shibs!