Three removes are as bad as a fire (Metaphor)
By removes the steps back are metaphorically meant, the narrator says that as many steps back a person is that much he is making worse. And when it's getting worse it arises anger, and anger causes a fire. And that fire is able to burn all the bridges to one’s dreams.
For a word to the wise is enough (Metaphor)
Means that wisdom comes in shortness. It is enough a few words for a wise one to make the things clear and explain the sense. And it is not enough thousands of words for a stupid one to prove him anything. This is very sensitive material to find right words to be understood, and this talent comes with learning as Poor Richard teaches.
Idleness taxes many of us much more (Metaphor)
Given analogy lights up the subject for lazy, for those who are wasting time and never pay any attention for that. If to come through the time that has been spent useless, as the book teach, one would come to the conclusion that it was a total loss of not only time but many opportunities. And the book teaches not to look back, but to get up and never waste the time, to start looking forward, many steps ahead. One always should keep believing in his dreams and they will come true.