How long will it take them to issue you a certificate once they have recommended you for approval?
How long has the registrar been in business, and do they have any European or Far East affiliates in the registration business?
If you will one day be going for ISO14000, does the registrar support this standard as well, and would they be able to combine (thereby reducing the man-days at your site, and $s) the ISO9000 audit with the 14000 audit?
Who does documentation assessment and who does the audit? What is their experience / qualifications?