By going through all the above statements in my book, I got the following questions.

Why are tertiary alkyl halides obtained as major than secondary or primary?
It seems that hydrogen from tertiary carbon can be easily replaced by halogen than from secondary or primary carbon. If it is so, why is hydrogen from tertiary carbon can be easily replaced than from secondary or primary?
Why is fluorine and iodide not considered in case of free radical halogenation (as you can see, the first two lines of the above passage extracted from the book, mentions only chlorine and bromine)?
Why is tertiary alkyl halide not produced in the above example? Even if we think it might be produced in less amount, it should have been greater than primary alkyl or secondary alkyl halide, is n't (because of the order)? It seems the reason for tertiary alkyl halide not being in the equation is because of either, it might not have formed or it might have formed in lesser amount than primary or secondary. If it is either any case, it would violate the order mentioned in the book.