The RadMap can draw shapes based on GeoJSON literals, therefore, it can draw seats or whatever shape you need. Although, you should note that the RadMap does not provide an automated logic to create the GeoJSON. You should do it from scratch.
Click logic or other shape-dedicated manioulations can be further handled via the shapes' events - shapeClick, shapeCreated, shapeMouseEnter and shapeMouseLeave
You can find attached a simple example which illustrates how you can handle such a requirement. Although, the client-side logic to manipulate items in a cart and further should be additionally designed.