I'm wondering how seo for a blog works... do you just optimize per page? or do you have to do it for the entire blog? If I submitted a page to a blog and google has indexed it and then I start doing seo on it is there any penalties on for it?
I optimize each page for a specific phrase or phrases and ideally try to keep the pages in agreement with the theme of the site. You can change the SEO elements of a page as many times as you want as long as you don't violate search engine guidelines.
is it bad to change the title of the page? I heard if you change the title it might take a few weeks to get reranked
No problem. Do change the title if the first one isn't descriptive of your content. It might take a few weeks for that new title to show up in the search-engines, but in the meantime the original page won't be out of them.