What Am I Riddles

Question: Some use me, while others do not.
Some remember, while others have forgot.
For profit and gain I'm used expertly, I can't be picked off the ground or tossed in the sea.
Only gained through patience and time, can you unravel my rhyme?

Question: What goes back and forth constantly, but never in a straight line?

Question: People look at me all the time. I have a large vocabulary. I can teach people a lot of new things. I can be mysterious, funny, adventurous, romantic, scary, and sad. I tell stories. I can take people to other worlds. What am I?

Question: What can be white and yellow at the same time?

Question: I give light by night, but not by day, Am wicked but not evil in any way, Wax for the most but always wane, Except when I'm out, I stay the same. What am I?