Your browser will download the file to your disk. When you click on these links, the logo of choice will be displayed in your browser window. If that is the case, then save the logo file or template from that specific helper application. The image is, by definition, a rectangle. These pictures are on a white background.
Picture is rasterized.
Resizing is problematic, although downsampling often works okay. Because the sizes given here are large both in resolution and file-size, you will probably want to downsize as needed before embedding in you document. Because EPS files are vector based, they tend to size and scale better. Also, because the eps format is not a rectangle, the logo extends only over the region where the logo appears. Thus, eps format may be more useful for inclusion in applications with a nonwhite background.