With this you can easily set limit using max parameter on foreach, and you can also add classid in url as parameter if you want to filter on that. http://ez.no/doc/ez_publish/technical_manual/4_0/reference/modules/content/fetch_functions/keyword_count
But look like you want to link directly to the articles that use same keyword, so you should probably look at: http://ez.no/doc/ez_publish/technical_manual/4_0/reference/modules/content/fetch_functions/keyword