While you can use your season pass to get into Hawaiian Falls that day, only those with the special wristband are allowed to stay for the after hours event. Wristbands are distributed with purchase of the tickets from the PTA
No. You are purchasing a single use ticket to Hawaiian Falls which can be used any day of the season at any Hawaiian Falls location. You will need an admission ticket for the day of the event to get in the gate and a wristband to stay after hours.
You can order tickets here