Rel canonical on categories

[LGV]

Is it ok to add rel canonical on categories (content_list file)?
<link rel="canonical" href="http://www.sitename.com/category/<!--CATEGORY_NAME-->/" />
I see i have lot of pages related to categories like:
http://www.sitename.com/category/Teen/
http://www.sitename.com/category/2/Teen/ctr/2/
http://www.sitename.com/category/2/Teen/ctr/7/
Should i leave them without or should i add rel="canonical"?

[admin]

Well, you can do it with SmartCJ

Should you add it or not - ask google for example )

[LGV]

Thank you admin, i asked Google and i got my answer
Regarding description, I added this code in content_list but when i check the page source for one of category, instead of seeing that category description i see the code:
<meta name="description" content="<!--DESCRIPTION-->" />


I use other codes for title, ex: <title><!--CATEGORY_NAME--></title> and this works great, but how can i solve the description problem?

[LGV]

..and how can i change this adress: www.sitename.com//?force_template=categories‎ into www.sitename.com/categories
I suppose i can do it from htaccess but what code to use? It is good to change the address or to leave it like that?

[admin]

If you need a description for a category - <!--CATEGORY_DESCRIPTION-->

I suppose i can do it from htaccess but what code to use?

Yes, read about mod_rewrite

It is good to change the address or to leave it like that?

Good for whom ?