Don't know about history of the file.
For what the options do, Primary= is the image file used, Alpha= is the file with the alpha channel, the other two I know are in the CCG, Hint=Dynamic (I know of no other settings) is something you use only in specific situations, and Tile= can be changed between a small number (4?) of settings, for more on what Hint=Dynamic and Tile= do check your CCG, I remember TRS04 had it.
There are no more