If you are website owner and building a links to your site than discuss here how much its affects your rankings in search engine? You found it works for you for long term?I checked many Hot popular bloggers not market their blog mostly They only researches and post in their blog. I used many tricks and observed they just spent few time in commenting in official blogs like adobe blogs,Intel blogs,Google blogs etc but their purpose not for link building. Google only find original content providers and it is master in it.Please provide what's your opinion in this?
I don't find duplicate content a serious issue on SEO. Consider some site where they have duplicate content as Wikipedia. But, they still have good PR, traffic and Alexa ranking.
It is best to have unique content promoting your site, so for article submissions or blog posts in our experience (we have 5 sites in top 3 for 5 different niches with 8-12 million results) make them unique this way it gives Google an excuse to crawl your sites on a regular basis.
Link building is a crucial part for every sites. But after the installation of panda, Backlinking getting less priority in the case of PR. Google now consider unique content first and then backlinks.