Agreed, building on what you already have is a much better way to go than starting from scratch. I'd also suggest adding a new page focussing on subject matter surrounding this keyword. Firstly, this won't interfere with any of your other
SEO, and 2nd, if you do a good job of it, you could end up with 2 pages ranking on the first page of the SERPs for this keyword.
Articles are a great idea, but personally I prefer to have the articles on my own website - they are viable landing pages in their own right, perform well, and hopefully attract a few links to me. I do give up content to article sites now and again, but for me the benefit of the content to my own site outweighs the couple of links I might get from submitting to an article site.