It's great to do it both ways, I think. Break it up a little. Generally number 1's good for paraphrasing a historian, while 2's needed for direct quotes of longer nature.
You generally don't have to name the work/title in exams, although I think ancient titles should be. Just my opinion. Definitely no page numbers needed, and, personally, I would never encourage students to memorise book numbers - it detracts from learning more quotes.
So in the exam:
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As mentioned by Pliny the Younger, in his
Natural Histori, Vesuvius was 'a very big mountain'. He also tells us that it exploded with a great bang.
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[Edit: Er, in the exam, you underline, not italicise. Underlining's what you do when you can't italicise.
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First sentence = direct quotation, second sentence = paraphrasing.
For assignments, ask your teacher if they want you to footnote, and how they want you to reference. Noone here can tell you how to do that, it's up to your teacher. Stylistically, though, the way above is a good way to incorporate quotations into your essays - having a combination of direct and indirect citations is the key.