The short answer to your question is YES YOU CAN USE GOOGLE ANALYTICS. But to be exact, you will need to develop a script to connect to the GA Reporting analytics to extract segmented data.

There would be 3 major components to this functionality.
1. dashboard graphics - you can puchase templates online which have very nice looking graphics that you can weave into your superadmin

2. GA Planning - understanding the structure of your website, how to filter and segment information to isolate each individual vendor and generate queries to extract individual vendor information

3. GA Integration - The development aspect of connecting your platform to GA's Reporting API, delivering proper query notation to extract information, and rendering the information into your template format for front end display

So depending on if you're a developer yourself, this can be a low cost DIY project where the only part you will most likely need help in is in the GA Planning part. You can consult an expert like myself to help you draft to ensure you are capturing the right information for your clients.

Alternatively, I myself am building a platform that allows users to easily deliver infographic type reporting with highly segmented GA information. We may be able to deliver a cost effect way for you to integrate with your system. Check out www.pixall.net to find out more.

I hope this helps to solve your problem and feel free to schedule a call to discuss any details or if you require further assistance with the GA planning stage.

Cheers,
Jennifer Ping