According to the website, the actual shooting will start 1 March. You may enter as many times as you want at the local level.
I called Royal Hawaiian Shooting Club and they don't have any more details than what is on the website.
There are categories for Junior, Men, Women, Military and Law Enforcement. Eligibility is limited to true amateurs. If your are part of a shooting team, or have placed in the top 10% of a sanctioned competition, then you are not eligible.
The grand prize is $50,000.