Legal Advice Needed: Tobacco Sale To A Minor (hawaii)

Using a throw away for obvious reasons. Anyone with legal background who could assist me, please? This is the first I've gotten into a legal situation. In the state of Hawaii.

During a shift at a convenient store, I sold tobacco to a minor (Honolulu Police Department sting). I asked for and checked ID, but I incorrectly calculated the age (I even said the birth year out loud) - just a really stupid mental error on my part. I was given a ticket with a summons to the District Court of the First Circuit, City & County of Honolulu. Does anyone have experience with this? Some questions I have:

• Is this a violation or a petty misdemeanor? From my research, the relevant Hawaii statute is at the following: Title 37. Hawaii Penal Code 712. Offenses Against Public Health and Morals, 712-1258 Tobacco products and electronic smoking devices; persons under twenty-one years of age. I only see a fine as a penalty (no prison sentence), which, under my reading, would qualify this offense as a "violation" and not a "misdemeanor/petty misdemeanor."
• If this is a violation, what is the difference between a violation and a misdemeanor? Any implications for court that one should be aware of (e.g. is there a plea?)
• Should I consult a lawyer? If I don't hire a lawyer and show up to court, what are my realistic expectations?
• Is there any possibility this could get dismissed?
• Is there anyway to ask for a postponement or expedited court date? The date that was written down is when I'm away on international travel, which I can't miss.
• Any other advice?

I've learned my lesson...it was honestly such a dumb mistake, but I was in a bad head space. I calculated "23 years old" actually in my head. In any case, appreciate any help this subreddit can provide!

Thank you in advance!