For 7: References and sources are a must, unless everything is your own work. They should not be put at the end of the slides because the public does not have access to your file, so they cannot go back and forth to properly read the source like they can in a paper. The way I do this is simply putting “Source: blablablabla” in a smaller font, so the reader can easily recognize it as a source and ignore it if they want to.
For 8: This greatly improves the public’s ability to ask you questions, as they can just say you “Please go back to slide #X”, instead of having to explain the content of the slide.
Keep in mind these are used in my scientific academic background, perhaps outside of it they are not as important.