As far as how long to study...I confess that after reading the 72 pages of text in the front of the REA book and looking up literary devices/terms, all I did was take the practice exams and read the explanations for wrong answers. If I count up the reading time and the time to take the three practice exams, I
maybe spent seven and a half hours on this. I got a 78 on the exam.
If you don't have much experience with reading literature, you might want to study more. For me, the hardest thing was the early modern English pieces (what many people think is Old English) where everything is spelled phonetically and the language patterns are archaic. That made me cranky, as it always has.
But luckily, I didn't encounter much of that on the version of the real exam that I was given. I actually did better on the exam than on the practice tests.
Best of success to you!