Hello, my name is Gonadbubbles, and I'm a noob. . .

(you say "Hello, Gonadbubbles" in masse)



What skills are available as Secondary Skills?

Is Fishing, Cooking, and First Aid the only combination or is there something else available?

nothing else is available, those are the 3 secondary skills and you can learn all three regardless of your primary professions.

The only combination. Get them all. 
First aid can be very very helpful. If your class has stun equivalent you can heal yourself in the battle
Cooking nothing wow here, but so easy to lvl. You just cook what you get. Useful to cook +smthing food (eg +20 sta and spirit for 20 min)
Fishing not very exciting. But if u r waiting for someone or have a guild meeting helps to kill time.