Wow - that is a lot of questions within a question.
Trying to rank for highly competitive keywords is as the name suggests hard, I would either go for the long tail keywords or finding little niches within the industry and rank for these. While you are doing this you are building your DA, et al and therefore should start ranking for the more competitive keywords.
It doesn't in theory matter how many keywords you are ranking for, but remember the more you do, the less you can concentrate on them and you will spread yourself to thin and not actually improve any. Especially if its just you I would concentrate on a few keywords which will drive you high converting traffic.
I would track keywords in two sections (brand vs non brand), as branded keywords I would hope you are always in the top positions.
Ranking the pages, yes look at "Title, H1 Tag, Description, Meta Data, Fresh Content and using the keywords on the page" but also look to build decent, relevant links into the page.
Use the Page grader to find some quick wins to help boost these pages. They usually tell me some of the basic things I have missed.
Best practices for link building - http://moz.com/beginners-guide-to-seo/growing-popularity-and-links I would read this article, I could try and explain here but I would just be repeating the experts. I would recommend reading http://moz.com/learn/seo to further your reading.
Hope this is useful for you.
Thanks
Andy