I get the point about duplicate content, that's something I had heard but not really delved into because, well, decent architecture usually means not having that sort of stuff around.
The more I hear SEO "experts" go on about things, the more I think it's a bit of a scam. Scam is probably the wrong word, as I'm sure many SEO people are well meaning, but the more I look the more it all seems like snake oil.
At one point I put together a pretty basic site with one backlink and barely any attention to content and accidentally ranked #1 in Australia for "make money". One particular page on that site is four paragraphs I threw together and it's made $24k in four years for no effort since. I've had a few other events along those lines too, mostly leveraging the past property I built up and using that as a backlink.
There are plenty of great search resources out there.
I would suggest to start at http://searchengineland.com to get a better sense of the landscape, especially everything Danny Sullivan writes