Firstly, TIL has http://www.imperial-library.info/forum, and if your questions refer to their site you might be better off asking them there.
Secondly, in case you're not aware, the Imperial Library is maintained by fans, not the developers of the games. Some of the content there is summaries, speculation or exploration compiled by fans, and you may need to check the author and what section of the site an article is in if the source is of concern, but it should always be given.
On unofficial sources: well, here's the thing, Bethesda has very rarely given word on what we should consider official. What texts developers write outside of the games, or even what fans can come up with, can often be very useful in exploring concepts in lore even if you don't take it as concrete truth straight away. The officialness of a piece is often unimportant, and debate around it usually pointless. A thing can be considered on its own merits, without bothering about who endorses it.
And what C0DA is: there's a few recent threads that asks that, you can search for them. And http://c0da.es/t/c0da's a link to the thing itself. It's a text by Michael Kirkbride, with illustrations by various artists on another section of the site, which explores themes from Morrowind and the http://www.imperial-library.info/content/loveletter-fifth-era-true-purpose-tamriel, as well as implicitly confirming ideas that the "canon" of TES is irrelevant by comparison to personal interpretation.