Is there any context that I should know before reading through these books?
From what I know, "histories" up to a certain period cared less about accuracy and more about communicating a message about the people they talked about, is that correct, and does that apply to these books?
Thanks!
This is a great question and the exact right source to frame it.
This isn't my flair subject so I'm going to first and foremost direct you to some previous FAQs on how and why to read primary sources, which can be found here, and there's a good "Monday Methods" thread here. Here also is a thread specifically about Plutarch that, while it doesn't contain a flaired answer, has a good discussion.
But I have some basis in the subject, so take the following with that caution:
Personally, I think the historiography -- that is, the study of the historical writing itself -- is an interesting part of the history. Plutarch is telling you what he thought people of his age wanted to read about key figures from their past. That in and of itself is interesting. But anything you glean from that has to be taken with a considerable grain of salt.
Some specific warnings on Plutarch, and a source for it available on Google Books for more reading:
Plutarch wrote at sometimes considerable distance from his subjects. He's a first-century Greek writer describing, at times, the lives of people who lived three hundred years before his birth. That necessarily bespeaks caution.
Plutarch casts a moral "character arc" for some of his famous figures, where the goal seems first and foremost to tell a good story about human virtue and vice. The broad themes should be taken as examples of good story telling, but not necessarily good history.
For example, he attributes some (extremely compelling and fun-to-read) quotes to his "characters." He's one source for Pompey's famous boast to Sulla, that "more worship the rising sun than the setting." There's no way Plutarch could have heard those words spoken, and extremely unlikely he knew someone who did.
That said, these are some of the first primary sources I read in college, precisely because they're highly readable, compelling introductions to ancient biographies, and tell you a lot about history, the times, and the study of history. Read them and enjoy them... but don't take the words "for the truth of the matter asserted," as we lawyers say. Take them as a jumping off point for further reading.
And -- ENJOY!