By putting the name of your blog and/or category names in the <title> of every page you are telling the search engines that you want every page on your site. you;re basically splitting up and pr and linkage value into pieces
Sorry Canonical, but I must respectfully disagree with you about not having the site name in the TITLE tag. It's needed for accessibility purposes, and I'd rather take the small hit in ranking power to ensure that the user (especially if using an assistive device such as a screen reader) knows that they're still on the site. I do agree with you on removing the category title though, if it matters any to you.
Go ahead and use the keyword tag and repeat your keywords and phrases, but at best it will have little impact. At worst you may get penalised for it.
You won't get penalized for using the META keywords tag, Candise, unless you are stuffing the tag to the gills with keywords.