Use the Page up and Page down (PgUp/PgDn) keys to look up and down, respectively.
Access different worlds by clicking the "Universe map" button at the bottom right of the screen
Change your avatar by clicking "VIP" on the right hand side of your screen. From there, choose your avatar.
To add a friend, go to "Options" on the right side of your screen, click "Edit friends" and then "add"
Use emotes by clicking the "Actions" button right above VIP on the right side of your screen.

The options menu has a wide variety of different things, look through it to find them out.
You can enabled colored chat this way

HERE'S A BIG ONE: Go to Options, and you can click "Change Avatar View" to get a better view of the game.

You can also click the name above someone's head for a list of options. (Add friend, whisper, etc.)