The final format is no format:
http://www.loper-os.org/?p=309
>is the format simple, efficient, small?
Nothing could be simpler, and it's as efficient as you make it.
>is it open source, free, or at least without patents or some other shit?
The source is an inherent part of the format
>is it supported by large amount of software? for import and export?
Supportable by anything that runs on the same architecture
>is it malware? has hidden metadata and other shit? complex and proprietary?
All data is explicit
>does the format allow for huge documents?
All the way to the halting problem.
>what the format supports? formatted text, embedded fonts, images, tables, embedded files, hyperlinks, what else?
Anything your turing machine can do
>is it simple to open both for viewing and editing?
Could anything be simpler than spooling up a virtual process, pointing it at the first record, and telling it to keep going?
>are the editors of the format small efficient or bloated and buggy?
Vi-editable (or emacs, I'm agnostic) couldn't get more efficient.