Rand Fishkin updates his list of questions qualifying SEOs seeking to charge for consulting services -- they should be able to correctly answer most, if not all of them. Those hiring a new SEO professional or seeking interview questions for someone to bring onto the team can also use the list. The questions include: Name six tools or sources that will display a list of external URLs linking to a Web page. And, how can an SEO positively influence the ratio of pages a search engine will crawl and index on a Web site? Fishkin plans to post answers to the questions, too.