citing from a review
some authors cite from review introduction while others cite from review conclusion. Does it mean that I can cite from any part in review paper...? 


Yes: You can cite any aspect of a paper. Albeit, you should avoid citing a secondary source (i.e., when a paper cites another, cite the original source,* rather than that paper). It is sometimes useful to cite a particular aspect of a paper, e.g., [Section 3, 1] or [Theorem 7, 2], so that readers can find specific aspects of papers to which you are referring.

*Do not cite the original source without sufficient consultation.