What about internal link-structure? And using your key as anchor-text in the internal link-structure?
sorry, i forgot: also outbound links (use your keyword in anchor) to (good neighbourhood) high quality sites can improve your ranking.
Nice list . Its just that 15% is way too high density which can affect prominency for keywords. So below 7% is fine. Also keywords in meta descriptions is still a positive thing and is considered by most of the search engines.
hii Rezo i am not satisfied with what you have written. why do you think meta description tags are not important? they are infact very important from point SE point of view. we always make meta for the search engines, not for our visitors. if you carefully see the results(SERPs) for any keyword, you will find how important is description part. if you use keywords in descrip[tion tags, it gives you an edge over others and has the more chances of coming up in SERPs.
Just because google highlights the keywords (which in your opinion, should be present) doesn't mean it really has an importance. This is not a factor. If you look closer, it's just a coincidence that the meta description wasn't manually set and generated from the content, which contained the keyword and google highlighted it when you search. No importance for the position the meta description tag.
those are just basic thoughts, I guess you should research more on optimizing a website. They are lot of factors . . .