There are a few different kinds of Satanism and Luciferianism that have different views about what the two characters represent and whether or not they are one and the same. I imagine your confusion is because of this.

Also the vast majority of symbols that get associated with things like satanism are actually good. They tend to get demonized by people who don't understand what they are and then the satanists embrace the symbol for its newer demonized association with because they find it empowering to be shocking and edgy.

As for the music artists using these symbols. I don't really know but It seems to me that they are just doing it keep peoples attention. Its a marketing strategy. If people think you'r wrapped up in some crazy satanic conspiracy they will pay more attention to otherwise unimportant celebrity news and music videos.

I'm sorry if I'm wrong about this, but I get the impression from your post that you may be lumping Occultism and satanism together. The occult is a wide verity of religious and spiritual philosophies which mostly don't have much if anything to do with Satan. Some forms of Satanism and Luciferianism have a lot of occult elements and are under the umbrella of Occultism, but they are not the same thing.

There are several ways to interpret beings like Satan and Lucifer depending on the system of thought you approach them with.