Multi-language blogging improvements

I write in my blog in both English and Brazilian Portuguese and would love if My Opera supported multi-language blogs in a better way.

Currently I have linked my multi-language articles by manually putting a link on the top right of the article for the other language's version of the page but it isn't good because on the frontpage of your blog, archive, tag search and in the subscriptions news page when they are new the two articles show there making it a poor experience for both language's visitors / subscribers.
I know there's an option to create a group to have another blog here, but I don't like this solution so much and decided to keep everything in just one blog.

My idea of how a multi-language blog should work is the following:

• Each version of the article must have a different URL (for easily recognizing, sharing and for SEO purposes).
• Following the logic, each version must have its own comments (it'd be a mess mixing comments in various languages).
• Visitors on the frontpage would see the version of the articles in their preferred language (via browser's settings / My Opera setting) and if there's none of the preferred languages it'd fall in the English version (if there's no English version, well then there will be a language relevancy list to give the visitor the most common language version of the post). The same rule would be applied to the subscriber's news page, etc.
• The visitor must be able to switch to any other language somewhere in the page (e.g. via links on a top corner like I do currently or Wikipedia-style, or even better: a drop-down menu which says "Choose language" with a little flag next to it for easily recognizing).

To achieve this:
[Early concept] When writing a blog post there would be kind of tabs on the top or bottom of the post text fields where you could choose between the language versions of the same article... When the writer clicks to create a new article there will be just one tab (his preferred language) and a plus sign would allow him to add more languages versions.

P.S. I searched on the Web about multi-language Wordpress plug-ins to get inspiration for these ideas.