If the data is stored in a spatial table and the feature is defined as a point feature, then the cell scale can be stored as a property. You define which property sets the xscale and the yscale of the cell when you register the feature from the spatial database.
You then create a sphere cell in the cell library with a default radius set to 1. The scale in the spatial table will then scale this sphere cell according to the value stored in the database property for X and Y scale (HINT : make the X and Y scale value the same)
As for the color this also can be dependent upon a property. You need so set criteria (rules) and associate this to the color key in the symbology node for the feature definition.
Make sure you set the "Override cell symbology" so the sphere will take on all the symbology (color, weight, level, etc...) values for the specified record in the spatial database.
HTH