Look in Kautz's book. Or, the Army Regs. But basically, it's the same stuff as an infantry private, except for the stripes on the jacket and trousers. Now, an Orderly Sergeant, or First Sergeant, would have pen, ink and added paperwork such as a roll book, morning reports, and on and on. You weren't issued the 2nd shelter half until you got officers straps.
The 137th NY performed way, way better than the 20th Maine at Gettysburg. They just didn't have a self promoting blow hard of a Col. leading them. Maybe you should look up the history of the 83rd Pennsylvania too, they make the 20th Maine look like the rookies they were.
There are some very good books out there about the fighting on Culps and Lower Culps Hill. Vincent's Brigade had nothing on those boys at the other end of the line.