There's a great dadgad chord chart on my web site... swordforhire.org in pfd (pdf?) format... it's actaully a little too much for most beginners... Look for the link to Gear and Guitar Resources...

the way I learned how to play dadgad was starting with the Stan Rogers book, and then kept my eyes open at Garnet Rogers concerts, and James Keelaghan and Stepen Fearing and... and...

As far as the 'flat' tuning goes, I've never had call to do it...