reference site evaluation questionnaire

I am a member of an IT project team, and I was assigned for evaluating vendor’s reference sites. I am looking for an evaluation questionnaire and a checklist so I can send it to the reference sites that were given by the vendors. The questionnaire should concentrate on evaluating the response on the vendor support, software package (with detail), fulfillment of requirements, implementation of project etc…. I would like also to have some kind of weight age I can use in my evaluation.