No Category Base

I have the following permalink structure: /%category%/%postname%/

but RDFa Breadcumb uses /category/%category%/%postname%/
How can I get rid of the first “/category” part?

Another problem is that “%category%” doesn’t use the category with the lowest ID but the first (!?) category if multiple categories for a post are used.

Can you please fix that?
Thanks in advance!

See these links for reference:

http://ww.wp.xz.cn/extend/plugins/wp-no-category-base/
http://codex.ww.wp.xz.cn/Using_Permalinks#Using_.25category.25_with_multiple_categories_on_a_post

http://ww.wp.xz.cn/extend/plugins/rdfa-breadcrumb/