The passages in the Elite book are definitely hard, but you can definitely run into some passages of similar difficulty on the MCAT. Prep with really difficult material now and you'll be prepared for anything on test day
That is correct.
I made a 12 on my bio last year and for my retake this year I also purchased the TPR Elite. It is very tough but on my MCAT last year, the bio section was comparable in difficulty. My performance has been around 65% on elite passages.