Arcpy.mapping cannot add an element to a map document, but it can manipulate elements that are already present.
Therefore, what you will want to do (to do it in arcpy.mapping), is to have an mxd prepared with place holding layers similar to the your yet-to-be-created output rasters, preferably with your prefered symbolization already applied.
You can then identify the layer in the data frame by the name you have given it, and perform method operations like
layer.replaceDataSource (to point the layer at your new raster)
or toggle the layer.visible property (to turn off layers you don't need or turn on ones you want to show).
You can also manipulate other layout elements other than the data frame: TEXT_ELEMENTs for instance.
These, again, have to already exist in the layout, but by using the elementPositionX and/or elementPositionY properties,
you can "puppet" them on of off the layout. (Say, add 100 to the elementPositionX to a text element you want to hide)
You can, of course, modify the text of a text element, too.
So arcpy.mapping is rather limited, but there is a good deal one can, with a bit of ingenuity, do within the limits.
To make new elements, and add new layers, and whatnot, you will need ArcObjects
(You can still do it in VBA with or without ArcObjects by requesting a free VBA-in-Arc licence to use VBA in arc 10 or 10.1 (and no further))