Other than the burial ritual, which someone identifies as Lakota, there's little Native lore in this episode. Just Geepaw reminding Grace of the Native constellations he used to teach her when she was young. On the other hand, there's nothing stereotypical, which is good.
Bobby Stillwater (Gregory Cruz) has a bigger role in this episode. We learn he mentors Native youths, including the murder victim Ryan. We eventually learn that Ryan was Arapaho, which is plausible since Oklahoma has a Cheyenne-Arapaho tribe.
Geepaw calls Grace "Champuli," which we eventually learn is a Choctaw word. This is plausible since Oklahoma also has a Choctaw tribe. But the show doesn't identify Geepaw as Choctaw. Indeed, it doesn't say whether "Geepaw" is a grandfatherly friend of Grace's family or her actual grandfather. (Grace and her siblings give him enough attention to imply he's their grandfather, but they don't say it.)
Grace and company unravel the mystery of the murder victim. Ryan was a squad leader in Iraq when one of his troops was killed. Because of his sunny disposition, he kept smiling during the war and after his return. Someone killed him because he was too happy, which is a novel fate for an Indian character. (The killer wasn't Native, so we can attribute the misleading Lakota ritual to his ignorance about Indians.)
My take on the whole series:
Saving Grace isn't about the whodunits or the angelic lessons--both of which are standard for TV dramas. No, it's all about showcasing Holly Hunter as a hard-talkin'/drinkin'/lovin' woman. If you enjoy this kind of character, you'll probably enjoy Saving Grace.
For more on Schellenberg, see Schellenberg's NBA All-Star Promo and August Schellenberg on Grey's Anatomy.