Loading a brush set is easy with the Preset Manager and you can save time by organizing them too. Just go to Edit > Preset > Preset Manager in CS6 or Edit > Preset Manager in previous versions. By default, Brushes is the default Preset Type. Simply click the Load button and navigate to the brush set you want to load. To arrange the brushes, click on the first one and hold Shift to select a range or Ctrl/Cmd click to select random or just click and drag the brushes to arrange them. You can move the often used brushes to the top of the list.
The “Markers” are actually brushes, but are never used other than as a visual marker to separate different sets of brushes.