adding a full size image (banner) to the first page of the survey

Hi there, the Text/Graphic solution will work great but it will technically be a part of the survey and might be limited by the width of the question containers. You can also approach this by going after the Logo space directly via some code.
If you have a Logo already in place for your survey, you can replace the URL of the logo for a single page by using jQuery. You can also use jQuery to adjust the styling of the new image. Place the below code in the OnLoad section of a question on the first page via JavaScript:
jQuery('#Logo img').attr('src', 'https://www.pngmart.com/files/9/Text-Banner-PNG-Transparent-Image.png');

jQuery('#Logo img').css({"height":"auto", "width":"480px"});