More about Grid themes How Grid themes show in the legend.
Cells can store numeric values, integer and floating point, hence integer and floating point grids.
To identify values - click the Identify tool. Experiment with CellTool extension. Temporary grids are created as result of operationsl they can be saved as permanent grid themes. In Map Calculator, you can use lots of Map Algebra functions for more creative recoding. An example of converting ordinal factors to dollars before combining values is here .