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I have a client with a website that has gotten a bit outdated. We've already built his new website and optimized it, but I'm trying to figure out the best way to replace the site while doing the least amount of damage to his current Google rankings. He's ranking #1 for some very competitive keywords that are responsible for the bulk of his revenue, so we want to jeopardize that.

We've already built a new site and written all new content, although the homepage page title, h1 header and meta descriptions will all remain what they currently are. I'm also trying to keep the keyword density as close to the current site as possible. I am aware of transferring all existing site URLS using 301 redirects.

Can anyone provide any tips that I should use when replacing the site? Should I expect a slight rankings drop or am I worrying about nothing?

So I've actually already setup rich snippets on my page. If I use this markup it won't get flagged as duplicate content?

Is there a good way to display reviews that people have left on sites like Yelp, City Search, Google, etc on your own website without triggering duplicate content issues? It's hard to get reviews, so I'd like to make the most out of the ones that I get.