Google Chrome Extension working with Google Calendar and External Database (Knack)

I need some help building a Google Chrome Extension dedicated to companies which need to track the hours of their employees. The extension will analyzes some data from Google Calendar Events and deliver some reports. This Extension will work with Knack (which has an api) to access the User's data including his profile, subscription status, etc. Here is an overview of how it will work: 1. The user subscribes to the service through the Knack Interface (I will take care of this part). He selects his industry, add his employees and subscribe to a paid plan based on the number of employees. 2. The user can then use the Chrome Extension to add Google Calendar Events. When adding a Google Calendar event, some custom additional fields should be asked to the user such as: which employee, was he in vacation or on duty, whether he was working or on leave, what was the reason of the leave, etc. 3. Whenever the user needs a report, he can generate one from the Extension based on a set of queries made on previously added events (especially the custom fields) of the selected calendars