Autocross and Skidpad are part of the NSXPO event, its included in your registration fee's.
HPDE on the actual track is additional.
As for the cost and track time, it's being worked on and will be released in the near future once we have a few more things worked out.
Most likely there will be 3 groups for the HPDE track time, A, B & C leaving a lot of track time for each group.