The exact match avg monthly numbers from google are actual search volumes, as per what goog says. From my experience I would say that the search volume to actual traffic is close but not exact. If your site is ranking position 3 and not getting much traffic, you my try tweaking the page title or meta description to entice users to click
If you only have one site in the top 10 you will only get a fraction of the searches to visit your site, especially if you aren't number 1 for your keyword. Build more sites, articles, blog posts, ect... and try to fill up the top 10 sites with your own. Also, another tool you can check traffic with is tools.seobook.com/keyword-tools/seobook/
