It changes over a period of time
Think it changes every week
Could be less or more
You can also change the Photo if you want to
When going to move the cursor over the Bing home page keep a close watch for the small squares. There is about 5 of those one being for collapsing the photo bar with another for scrolling through those as well as the three "hot spots" or squares above. Each of the three square will simply have a different description regarding the photo being displayed.
As for the background that can change at any time of the day as well as during the week! You can also see Bing on the desktop an active background rather then looking a a solid wallpaper. It depends on MS as well as what particular random or other order MS had going at the time. As far as running the Bing Desktop I wouldn't worry about it on 10 if you decide you want to try that out as far as compatibility since it goes onto everything from XP and newer!
Actually I forgot to include the screen earlier which points out the 5 hotspots when arriving at the Bing home page I keep as a book mark on the desktops while set as the home page on the laptop I set up for someone.
As you can easily see the three popup descripters circled as well as the option to hide the photo bar on the bottom at the left and the scroll forward or backward arrows at the right each of those right about the photo bar itself which was tucked away from view in the screen there. The Bing Desktop app sees the background change daily and referred to as the Bing Daily Changer for that app you can download separately.
Got a lovely Japanese photo up today but can only find 2 of the 5 buttons you have marked
How do I get the others up
I was referring to the popup box explaining the picture. I haven't been to the Bing home page for awhile and was just curious about when they started using the popups.
You never know what MS is going to be trying next since that seems to always be a work in progress. I simply leave it set for the default search engine to avoid Google bots and other rather lame engines like Duck2Go seen with FF and the other open source browsers.