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Ahh yes, the delete or dilute dilemma

In my experience, only sites with very few links can get away with dilution. If your site has thousands of links, and a large percentage are exact anchors, you'd have to engage in some very obvious bulk link building to dilute things quickly and sufficiently. In that scenario, best to find a way to remove the links, either by reaching out to webmasters or through a disavow.

The pic is actually from the blog post (though it is also used elsewhere), but the link to Rand's Google profile is likely there because the post identifies him as the author, links to his SEOmoz bio, and his SEOmoz bio has a link to his Google profile.

My first thought was to look for Schema code identifying the author, but that wasn't present.

Since you're running a test specifically for AdWords, you aren't going to want that test page with no nav to show up in search results. Just use a Meta robots noindex tag on the test page, or block it with robots.txt. The page will still be user accessible, but Google won't look at it as duplicate content.

There is no fixed number. The most significant factors are going to be threefold:

1. What does your historical link growth look like? (obviously this doesn't apply to a new site)
2. Will Google be able to correlate new link growth with an event? (Social promotion, press release, site re-design, etc.)
3. The quality of the links you are building and the way in which they are built (anchor text, DA, PA, etc).

From what I've seen Google takes a baseline, a "normal rate of growth" for both your site and your niche. If you site has had steady or stagnant link growth for years, and all of a sudden you start building a ton of links, that can be a red flag.

For a brand new site, things are a bit different.

Google is going to try to determine, A. have other sites like yours grown this way, B. are these new links spammy or manipulative, and C. does your link growth correlate with something in the news, some social signal, etc.

Of course, at the same time your site will be analyzed from an on-site perspective as well, so if your on-site SEO isn't up to snuff, or you've got duplicate content or indexing issues, link building may not help much regardless of quantity or velocity.

So again, as EGOL said, there is no fixed number. Just try to see things from Google's point of view and keep your link building above board. If you use quality inbound marketing tactics to build links, you shouldn't see any problems.

Sure, Google's Penguin update has keyword level components, and Google has been penalizing sites at a keyword level for many years when they find a site with too many links coming in using exact match anchor text. Depending on the scope of the problem, there are a number of potential solutions. This post might be helpful in terms of potentially fixing the issue: http://moz.com/blog/google-disavow-tool

It's always been just a usability thing. If your domain name is memorable, people tend to type in the www. automatically when trying to navigate directly. However, this is changing over time, and as you can see with Moz.com, no WWW, it clearly isn't a big deal