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Through popular (mis)use, the definition of "trolling" has been broadened to the point where it no longer has any real meaning. Most of the things mentioned in the article are not actually trolling, at least not in the sense that the term was used when I was a regular poster on Usenet (where, to my knowledge, the term originated). In the simplest sense, "trolling" is when someone makes a post with the primary goal of generating angry responses (usually by being intentionally inflammatory). And if I remember correctly, it was partly a portmanteau of "troll" and "trawling" - as in, "trawling for replies".
"Unintentional trolling" is a contradiction in terms IMHO - just being snarky or acerbic isn't necessarily trolling. Flaming is not necessarily trolling either, though trolling can involve flaming. And a "true" troll usually doesn't have any actual investment in the topic he's trolling on - so astroturfing isn't really trolling either (similar behaviour, but different goals and motivation), nor is being a fanboy/anti-fanboy the same as trolling. There's no reason an astroturfer or a fanboy can't ALSO be a troll, but I don't consider the terms interchangeable.
There's also the notion that trolling is inherently malicious and/or always has negative results - which I disagree with. On the unmoderated free-for-all that was (most of) Usenet, I would argue that trolls actually served something of a useful purpose: they were basically the "selective pressure" that weeded out the witless and the insufferably self-serious. For example, intentional misspellings were a common troll tactic to bait spelling & gammar-Nazis - falling for that a few times was enough to "cure" most wannabe-English teachers (even if only out of embarrassment).
And while some may see this as an extremely callous view, there are also at least a few people in any given forum who are so obnoxiously self-righteous & self-serious that they're practically begging to be taken down a few pegs. At least on Usenet, trolling was often just about the only effective antidote - one of my personal favourite examples was the "olive loaf head troll":
In the above example, which behaviour is worse? Trying to get someone fired over a few fairly-mild insults posted online, or trolling that person by making them think they'd succeeded?
That said, I do think it's possible to go too far with trolling (and flaming for that matter). Even on Usenet, most people frowned on things like death threats or accusing someone of a criminal act. Then there's 95% the articles on EncyclopediaDramatica, which appear to written by people who believe that "trolling" is a contest to see who can be the most offensively-racist.
As for stopping trolls (at least the truly-malicious ones), the most effective strategy has always been simply ignoring them. But that flies in the face of the mentality that many online seem to have these days: namely, the belief that they have some fundamental right to never be exposed to anything that upsets or offends them in the slightest. That leads to people to respond by raging against trolls, which is just about the most counter-productive response possible. To a troll, that's like holding up a sign that says "you were 100% effective in trolling me, please continue."