I would like to use the images that appear on Bing's homepage, can I just use these or will I need to link to these, publish them with a photo credit, or have written permission?
You can't just use them without permission. See the ⓘ symbol in the lower right corner of the image on Bing, right next to the arrows for previous and next image? That shows you the copyright information for that particular image. You could follow that information and get a license — most of the images are from stock photo agencies and I doubt Bing has an exclusive right to them.
Note that clicking the ⓘ doesn't take you to a licensing page. It takes you to a web search for the title of the image, which tends to lead to all sorts of different places. You'll need to investigate each rights-holder a little more closely on your own.
Note 2: this is really off-topic for this site. I'm voting for it to be closed as off-topic even though I hope this answer helps you.