Build an Algorithm to Create a Scoring System for Questions and Answers

I want to create a total score, based on questions and answer. Here is a brief: We are a sales company that attend many customers. We have a problem, we are not being able to decide which customer is serious or not, as a majority of these customers, end up making very slow decisions or none at all. Hence, we ask each new customer a questionnaire, and based on his/her answers, we assign a Decision Index Score. This will help us prioritize which customers to handle first based on their eagerness in making a decision, and which ones to add in our CRM for a routine visit. I have a list of questions, that we ask our customers. We also provide the answers for these questions. (Choose the best answer, multiple choice questions) Now the specifics of this case are: Each question has a different importance for us. So if the customer answers all of them, the pointage system is not equally divided by the total number of questions, instead we are going to provide the most important questions. Each question will have three or two options, and one of them is "I don't know" which will be a zero. The total score must be based on this pointage. Also, we need working models of this system on Microsoft Excel, so we can test these properly, and make changes to the weigh points for each question if necessary. Requirements: Be able to put this algorithm into Excel, and customizable, if we decide to change the pointage. Also build this algorithm into a fully working web interface. A page only for the algorithm to be tested.