I'm concerned that maybe I cannot find six quality recommenders. I know few people (my supervisor, 3 profs in my school who know me, few phd fellows who are professors in other universities now). I don't know anyone else except these people. I heard that the recommenders should be people with high status and preferably not colleagues or supervisors of the applicant. Is this correct?
Many people have found recommenders by contacting people who have cited their work or who have shown interest in their work at conferences. Also, your advisor may be able to suggest people who would be willing to serve as recommenders.
The status of your recommenders is not important, as long as they are qualified to discuss the significance of your work from the perspective of an expert in the field.
Yes, most of your recommenders should be independent, meaning people who have never worked with you, supervised you, collaborated with you, or attended the same educational institutions as you.