Knowing other terminologies in Adobe Flash CS4 and uses of it

I am just new in Adobe Flash CS4. I want to know what is the meaning of Symbol in Flash? What are the proper attributes that comes with it and how beneficial using it. What is the use of Paint Bucket tool and Pencil Tool. What do you mean by objects? What is the do you call the small arrow in right lower part of any tool that shows the properties or setup of a shape? Do we have a proper call for it? How useful the gradient colors in Flash CS4?

Please help me. Thank you!