Use nofollow for tags it's a very bad tactic.

Thats why i want to use sitemap so google can know... ok maybe it takes time but i want this to work.

The plan is: if someone search for Nexus 4 for example, will probably see the Nexus 4 tag in search result, with all the articles listed (inside the site) about Nexus 4 and NOT just a sinlge article.

Tags can not be ignored from search results.

Google Knows what tags are and how they work on joomla.