These request consist on an add-on for EB.
From the backend add the ability to create a sitemap.
Based on a backgraund image (optional) and a parameterized number of rows and columns and the size (H/W) of the cells a table conteining individual images from a palette of availabe pieces (single sit, double sit, empty, reserved, .....)
For the user, the ability of choose the seat when the payment is completed. I only use individual events, but in case that a user bought several seats he can choose as many as he have/needs.