Greg,
You can find out the name of the brush by switching from stroke thumbnail view to small list or large list view on the brush palette. I believe the brush you are looking at is the dune brush.
As for the colors, this is controled in the dynamic settings of the brush...a very neat feature. The Brushes palette provides many options for adding dynamic (or changing) elements to preset brush tips. For example, you can set options that vary the size, color, and opacity of brush marks over the course of a stroke.
For example, under color dynamics, Foreground/Background Jitter specifies how paint varies between the foreground color and background color. To specify a percentage by which the color of the paint can vary, type a number or use the slider to enter a value. To specify how you want to control the color variance of brush marks, choose an option from the Control pop-up menu. There are a lot of dynamic controls to check out. I haven't played with these settings yet, but here is an article that may help:
Understanding the Brush Palatte
Also if you select help in Adobe PhotoShop and go to the index and select brushes there are several sections on the dynamic brush settings.
ENJOY!
-T