The avenue XT does not support scripting. The main application does, but only appleScript on Mac OS, and the support does not extend to features added via XTensions. (XTensions can be scriptable, but none of the Quark ones except Scripting are, AFAIK.)
There are no automation features in avenue either. There are reusable XML templates; once I have done the text transformations necessary to the files I receive to ensure style consistency, I make a new XML file from my template, drag the main text flow to this, and let the parser do its thing.
Quark also has a Sequence XT that lets you select different boxes in a document and create a named sequence structure out of them. You can then drag that sequence on the avenue palette to have it all tagged at once, effectively treated like a single text flow (and supporting extraction of picture references as well.)
But to achieve true automation with avenue, you'd need to employ some clever combined use of scripting and a macro application. The ability to do this is directly dependent on the patterns (styles used, box locations, box names if tagged with such) in your documents to make them amenable to automatic processing. If there are multiple stories in a file, what would permit the software to recognize which boxes make up a unique story group?
If your interest is mostly in automation and batch processing, look at some of the third-party offering. I'd suggest you get some demos, maybe provide some sales people with a sample file or two to get their input, and try to run some live tests on these. Some one is going to have to actually try this with your files to figure out what will work to handle them.
Check out WebXPress at Gluon, they mention automation abilities for the pro version - see http://www.gluon.com/
There's also a product called Atomik XT, http://www.easypress.com
And iCPS from PCI at http://www.pcipage.com/ has some nice features (I've worked with this a little bit, only know the others from demos.)
Good luck,
- John