Well, you can always sight read the lyrical stuff in the Arban book.
It`s always a good idea to shake hands with your judges. Be friendly. As for scales, obviously, a B flat trumpet only has a range of 2 and 1/2 octaves, so the only ones i would attempt at 2 octaves would be F sharp through C. As for your chromatic, just play the entirity of your comfortable range. Hope this helps. And nerves only make auditions worse. good luck.