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Chris has given some great advice there. As a side I'd also recommend checking the site you are linking from doesn't come from a 'bad neighbourhood' and have lots of spammy links pointing to it. You can do this by checking on opensiteexplorer and checking the of quality external links and that they themselves also come from a relating category/niche.

In my opinion most definitely. I think I remember reading that up to 80% of searched per month have never been recorded before. This means that there's nothing to say your content won't be searched for in future. I'd also say that by creating this content you are building an authoritative presence that can help in with your internal link structure to enhance rankings for other pages that may contain more popular search term and aslo link juice to any other sites you may own.