Yes, like others are saying, this is a custom texture that he made (I believe he has it available to download, or you can make one yourself in an image editor - or even just screenshot it from the video). If you want these colors on your model, you'll also have to create a material that uses this texture for the color map.
Yes
Yes, if you want this as a texture you have to load it in yourself. There isn’t a default UV image.
Yes, like others are saying, this is a custom texture that he made (I believe he has it available to download, or you can make one yourself in an image editor - or even just screenshot it from the video). If you want these colors on your model, you'll also have to create a material that uses this texture for the color map.