I'm not a pro with Google docs either but I have used it a bit. I'm not sure there is a way to export Google docs into a down-loadable file if thats what you were trying to accomplish. The export function seems to just export the doc into a webpage format.
One alternative might be to use Open office. Open office is a open source "Microsoft Office like" suite which will allow you to create your files and save them in a format that most people should be able to read/open.
I'm not sure this really solves the issue because you were trying to use Google Docs as a collaboration tool. I can't think of a way to use Google Docs to "Download the latest copy" of a document from your blog. You'd have to manually export it, format it and upload it into your blog.
The Open Office option is only really usefull if you don't already have an office suite and were looking for an alternative such as Google Docs instead of shelling out big bucks.