Martin,
There is no variable for the "user" (yet), if you want it, I suggest you make this a feature request. Perhaps Kirk et al, will then implement it.
The name of the folder (or name of the contact sheet) of the file can be determined with the variable {folder}. The full path with {folderpath}. You can use all available string manipulations (eg. {folder:6} etc.) on these variables.
Does this answer your question?
