Didn't get you, explain it in more detail.

Well it actually depend on the blog/site you are commenting on.. Some includes a field for you to place your site or url, there are also blogs with keywordluv as they call it but it is pretty much not used by high pr sites. This is why comments on relevant sites is important, to avoid spams.

Yes, they are referring to using Anchor text vs your Company / Domain name to get backlinks also known more recently as naked links.

I agree, using varied anchor texts is the best method but you need a little of everything to have a natural looking profile

i think you need high quality blog post

Yes it's effective if you comment on site that is relevant to your niche.

Diversity is the key. Do it all, Keywords, your name, others name, and raw url.

If you got a place to put the keyword, why not? But if there is no option to put it like profile backlinks etc. you can skip it. But remember that using exact keyword is nothing but the only way to have a perfect back link and thus a good rank of your website to the search engine.

As far I understood from your question I would vote for blog posts.