Yup it works. But a lot of factors are involved. These are nicely explained in simple language precisely in the book

Yes it works as long as you follow the instructions. And it is easier to keep the weight off after you have lost it with this plan...

It will if you stick to it.

Well, yes. If you actually do it properly. I wouldn't recommend buying it though... Just stop eating carbs(max 30g per day) and eat at least 20g of protein per day. Try to exercise at leat 4 times a week. The exercise should be small whole body strength exercises preferably with weights like dumbells. The exercises should take about 15min of your time per exercise.
Good luck on your journey.