bad and good?

- If you're an American citizen as stated on your profile, there's no reason to sort out visa to move to HI.  HI is a state, not a foreign country.

- The best about HI are weather and scenery.  The worst are high cost of living, limited employment opportunity, and for many people, island fever.

- There's no winter in HI temperature-wise.  Job-wise, it's more than likely everything you'll find would be part time so it doesn't make much different.

- Oahu offers more jobs, but it also has the highest population so there's more competition. 

From your post, it doesn't sound as if you know anything about HI and haven't done any research at all on the state.  Perhaps you want to rectify that first before planning to move there.

Your post is rather strange because American citizens know that Hawaii is a state and requires no visas or any other special paperwork, so I doubt that you are really an American.  It's no different than moving from Washington to Oregon ---you just go.  All of your questions can be answered with Google searches. Look on the major job sites for career opportunities in your field.
I've heard that it's very expensive to live in Hawaii, so it may not be a good idea to go there without having a job first. Do your research, get a job, find a house to live it, and then move.
This article is about how expensive it is to live in Hawaii.
http://www.newsweek.com/most-expensive- … ore-628977