Parameters and templates are very powerful time savers in terms of new documents, and output generation. The way I have them setup is all of my parameters only exist at the project level. This way you only need to go to one location to update all the relevant information for any given project. The project parameters can flow down into each document (schematic, pcb, draftsman, etc), it is absolutely fantastic. And when i go to generate a document package, I hit one or two buttons and the file naming is generated via the parameter information as well. Very streamlined, I think it could be one of altium's best features.
For file naming you can make concatenated expressions like this:
=assm+'.'+printassmrev+OutputName