You might consider signing up as a member of the Scottish Tartans Authority at:
http://www.tartansauthority.com

Members can access tartan information such as thread count, date, and most tartans have a paragraph or so of information on them.

Other than that, the only reference I can think of that will have some of the newer information is my own [img]Compendium of District Tartans[/img] which has all the information you are asking of, for both the newer and old tartans, but only district (in other words, no clan or family tartans).

Aye,
Matt