A book has been published about the 10th Texas Cavalry that you might be interested in. The book was written by Chuck Carlock and is titled HISTORY OF THE TENTH TEXAS CAVALRY (DISMOUNTED) REGIMENT, 1861-1865. It was published in 2001 by Smithfield Press (located in North Richland Hills, Texas). The web address and e-mail address for the company are www.dfscott.com and firstname.lastname@example.org
Your ancestor is listed in the roster in the back of the book. In regard to flags of the 10th Texas Cavalry, two flags of this unit are depicted in the following book: Sumrall, Alan K., BATTLE FLAGS OF TEXANS IN THE CONFEDERACY (Austin: Eakin Press, 1995).