The second option is the best, at least from my experience. If you not only promote one product, its better that you do article marketing for specific tools. Since the coverage every each article marketing campaign will be very specific [ per specific tolls ], you will get the result more faster. In other words you will dominate per specific tools keyword, and it will be give any ranking value to your main/general tools keyword's ranking.

Yes totally, mix it up, the most important thing is to provide value to your target audience. Just make sure to use keyword anchor text.