Hi Lord. Welcome to the forum.
You can find a lot of answer in the next post; http://www.edgeent.com/animaforum/index.php?topic=6.30
1) I know that there are 20 different character categories to choose from for character creation. Could you tell me what a few of them are?
For this, a good explanation can be found in the above post.
2)I noticed that you can choose from a number of martial arts styles for your characters as well. What are some of them like?
There are 20 martial arts; 10 basics (like Kung Fu or Aikido) and 10 advanced / supernatural ones (Selene, Asakusen...). You can combine them to create your on personal style.
3) What are some of things you can do with Ki Domains?
Is quite extensive... from inhuman skills, like run above the water or cut fireballs with your sword, to advanced combat tecnics (that you can create by your own).
4) As for magic, its pretty clear what you can do with some of the 11 different paths (Air, Water, Fire, and Earth in particular), but what about paths like Essence and Light magic (I'm assuming Light magic involves things like healing, but does it involve anything else in particular)?
Light involve all positive energies, not only healing (in fact, other magic paths like creation are far better for healing), but it also has light attacks, shields...
5) One last question. I know you can play supernatural entities in the game. What types of supernatural entities can you play?
In fact, the "main" setting is for human players (or nephilins ones), but in the DM section are some non-human entities as well as rule to create your own races.
I hope that this was form help to you.