No, this isn't too complicated a question.
I just assumed wrongly that you were already using a metadata plugboard.
It is best to not store "junk" in the calibre metadata, but to separate them into different fields, e.g. the title field, author field,
rating field, series field, etc.
You can use a plugboard (Preferences ==> Import/Export ==> Metadata plugboards)
Example -- I use the template:
Code:
{title}{#subseries:| (|, }{#subseries_index:|Book |)}{series:| (|, }{series_index:|Book |)}
for the title.
When I send a book to my Kindle, the title is modified
in the exported copy only, to include the series and custom column #subseries.
But the title inside calibre is still
just the title, which is more orderly.
The template language is pretty easy, but that guide relates to the template language itself, not the various places you can use it.
For example, if you want to add the rating to the beginning of the title, like so:
4 stars - Wizard's Bane
You'd use the template:
Code:
{rating} Stars - {title}
Plain text is included as-is, anything in {brackets} is replaced by that named metadata field.
If you really want to just use the ISBN as the filename, you can change the filename in Preferences ==> Import/Export ==> Sending books to devices as mentioned in the GUI section of the manual:
http://manual.calibre-ebook.com/gui.html#send-to-device
The template:
Code:
{identifiers:select(isbn)}
will
select the isbn from the list of identifiers.
Note: If you have ever configured your device (see screenshot) you will need to use the Filename Template option there, since it still contains the default, and it overrides the above setting.
But I really do think it is a better idea to use plugboards, they are quite powerful and can really help you keep the metadata better organized.
Please feel free to ask any questions you need, especially if they have to do with setting up plugboards.