So, I think this is a great question and underscores a very important part of SEO - it's not black and white. Some links are obviously paid, others are not. Then we have the middle where we have to interpret what is being talked about as "paid" or "incentivized" links.
I wouldn't consider any of these "paid links" I don't think. The only one that I wouldn't say this about with 100% clarity is #3, but in that case you're paying for the article, and technically you could pay to publish an article without a link, right?
The problem is that money always muddies the waters. By buying an ad spot you are advertising yourself, but it's obviously marked as an ad. Also, if you buy ad space you're probably guaranteed to be accepted as a guest author even if it is "reviewed by submission".
By paid links Google is talking about links that are "meant to manipulate Pagerank". All links manipulate Pagerank in some way you could argue. So are all links bad? No. I could show many examples of paid links that add nothing to the page on which they are. THOSE are the manipulative paid links, not one within a blog post that has a publication price.
Also, going in and paying for a link within an article after the publish date, and especially in an article that was not written by you, is definitely manipulation, even if the link makes sense.
Those are my thoughts. I'd love to hear the thoughts of others, though this topic has been discussed to death in the past few years.