In theory there’s no limit to the number of widgets you can add. In practice, too many widgets will increase loading time and too much scrolling isn’t user friendly. Also, since you’ve set your front to display a short static page, I don’t think it will look good if the sidebars are longer than the main column.
If the image widget displayed only half of the image, then there was probably something wrong with the image or the dimensions you set or your browser. You can add it back so we can check (or give us the URL of the image you tried to use).