Nice post brinked, and fantastic contributions on behalf of many of the members.
The only item I would add here which tends, in my mind to "counteract" OOP and reinforce positive rankings - is to think like a brand. You touched on this in usability.
Brands, for the most part, care about the user. They cater to the user. They want to sell. They put the value proposition first. This requires brands to make usability one of the number one keys for success on their prospective websites.
And they send signals to Google that they are real, tangible entities and are therefore a least one "trust" level up in Google's eyes in terms of what they present. Sometimes reversing link penalties can be as simple as aggressively chasing down poor links, and replacing with membership, civic organizations and trusted, accredited sources at the city or topic level within your niche.
Often, improving brand signals alone can completely change the way in which Google perceives not only your website, but your back links as well.