Depends on what program you are running. If it is like windows media player then it is to stop the music or movie. If it is like utorrent then it is to stop the download. If it is iTunes or something similar to itunes then it is to stop the syncing process.
to stop loading a page on to your browser
toolbar option button
Image Toolbar
It's called the Quick LAUNCH Toolbar and its to the immediate right of the Start button.
No it is on the quick access toolbar.
Image Toolbar
The home button is generally used to take user to their default page. It depends on what toolbar you are using.
toolbar option button
The undo button.
spell check
spell check
Open the View menu and then Toolbars and then the Control Toolbox toolbar. From that you can draw a Command button. A button can also be drawn if you use the Forms toolbar.
Option button