What does the resulting data mean and how do we get them?
The cost per ticket figure indicates the effectiveness of customer care. However, it depends on what type of query is prevalent. You can have a business where most of the customer questions are simple. Or maybe on the contrary customer support deal mainly with complex questions that take a lot of time to explain.
The support cost per order is an indicator that summarizes the overall efficiency of the sales process. The lower the price, the more satisfied customers of your e-shop. If no troubles occurred during an order processing there is a much lower need to write to the support desk.
The number of inquiries per 100 orders could demonstrate a lot of things - bad UX of your web, poor information architecture, or chaotic process of completing an order. The more people have to ask, the more likely they are missing some essential information during the shopping process.