Extracting and citing wording from the books will not give your answer a clumsy or rot impression but again the citation should be relevant and your answer should not appear as a collection of abstract quotations from various book!! I think giving 4~5 times such wording in a question are more then enough. Take it as an upper limit for citing.

Answer to Second question should be given by yourself that how much you can retain. Initially every word and every comment from a foreign writer appealed to me very much, later i realized the same problem same as that of yours. I used to memorize the wording that could be used on more then one place, were simple in wordings and were more concrete and less vague. Same I would recommend to you. Going for long, wordy and less relevant wording will make it difficult for you to memorize the wording itself, remembering the name of writer will be out of question in such a case. If still unclear feel free to ask again.

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Faseeh