How to set automatic export of metadata with separate files for every dimension?

I can tell you one thing we do for our clients. We created a whole bunch of UD8 members that pull in all the metadata settings for each type of dimension in individual member formulas. We then make these into Cube Views that can be run at any time to show all the settings for each member (name, description, formula, text fields, etc). I've added these to a book for our clients that runs all the cube views and puts each dimension in its own tab. It's a little laborious to set up the first time (we have a standard set of custom items we've created we upload to every client's application), but it can then be run via a task scheduler of you like to pull whenever you like. 

You could use the exportxml functions to do this in a rule. However, you'll need to create rules to parse the XML to make them readable, or download to EXCEL as tables. Shameless Plug, the company I work for, has put out 11 utilities in PartnerPlace (one is Metadata Manager). Also, there is a free one by MindStream