It would be fair use only if used infrequently. For example, if you want to quote someone else's article in your article, that's fair use. However, if your entire business is dependent upon making snippets from thousands of articles, that's no longer fair use, it's commercial use.
No, you're wrong.
First, fair use applies to both commercial and non-commercial uses. For example, when Mad Magazine did a movie parody, that would be fair use, even though the magazine us sold for an increasing cheap price and is a commercial venture.
Second, the previous poster didn't really explain it well. Fair use is when a copyrighted work is used without permission in a way that, but for fair use, would be infringing, but which is not infringing because it is in the general purpose of copyright to allow such a use. It's evaluated on a case-by-case basis, and is completely fact dependent. This, any particular use might be a fair use, but not just any use actually is.
There's a test for finding out whether a use is fair or not. It has four factors, though it isn't a matter of adding up how many factors go one way or another, and depending on the case, one factor might be treated as outweighing another. Plus, it's just a tool; other factors can be considered too.
The factors are: 1) the purpose and character of the use, such as whether the use is for profit or not, whether the use would advance the progress of knowledge by resulting in something new or otherwise helpful; 2) the nature of the work being used, such as whether it is fictional and therefore very creative and worth protecting, or factual, and therefore not worth protecting quite so much (how a work presents itself is also often relevant in copyright; if you claim that something is a fact, even though it's made up or is just a hypothesis, others may get to treat it as a fact) as well as whether the work being used has already been published or not; 3) the amount of the work used, and how important to the work that portion is; and 4) whether the use will have a negative effect on the value or market for the work (positive effects are not considered).
Snippets of this type -- in aggregate, mind you -- have repeatedly been found to be fair use in the US because for the first factor, although the use is commercial in nature, it provides a benefit to society in being able to search for this material (which of course requires as much material as possible to be used in constructing the index, even though the index itself, as opposed to the results of a search, is not made available), the second factor may weigh against the use depending on the material being indexed, but it is not treated as being very important, obviously the whole work must be used to make the index for the index to be useful, so the third factor doesn't matter, and for the fourth factor, it doesn't harm the market for news articles to be able to find them and to see in one or two lines why they match your search terms. It doesn't matter if that's the business model.
And if you think this is extreme, look at time shifting, which is bad on all of the first three factors, but is sufficiently successful on the fourth so as to be fair use (in a general way, since again it is highly fact dependent)