Is it true that for your drivers licence Chapter 4 in the Dmv Book is all you need to study for it or what?
To get your driver's license, you will need to study the whole DNV book. This is because every chapter has its own importance. Chapter 4 only deals with Traffic Signs and Signals. Visit http://www.123driving.com/florida-driver-handbook.shtml, for a quick look.
No study the entire book
It's better just to study the whole thing don't rely on just one thing
No. The whole book is on the test since you need to know all of the rules of the road in order to operate a car - not just the rules in chapter 4.