"Dial in" is usually used in bracket racing where two cars of potentially vastly different power levels race against each other. You "dial in" your time - basically state up front how fast you'll run. There's a great explanation of bracket racing HERE

As far as "staging is at option of driver" all I can think of is that will allow you to deep stage if you so desire. See the section on THIS page below the picture of the christmas tree starting lights for a complete explanation including pros & cons.