This song is Gothic for sure. I mean, I know the other songs were meant to be Gothic, but I really don't know many Gothic songs. So here is an actual Gothic song.
A sailor offers to sink a ship for someone, in return for a wife, a house, and land. Spoilers: Things don't end well. I don't think it is Gothic, but it's kind of a dark song.
I'm actually not so sure if this can be considered Gothic, but it is pretty dark, and has a sort of Gothic-y aesthetic. I don't really know how to find the sort of Gothic music I think you're asking us to find, as I keep coming across Emo music instead. Oh, well.
I've actually read Dr.Jekyll and Mr.Hyde. It was an interesting read, and I might recommend it to someone who likes psychological horror and mystery. I think you'll get the best experience from the book, if you come in not expecting anything. (Also, Treasure Island is great, I'd recommend checking that out too.)
Unfortunately, there isn't much I can say about Edgar Allan Poe, as I have never read one of his books or poems. I would like to though someday, as he is a writer who has had a lot of influence over the years. His writings are definitely on my 'Things to Read Next' list.
He loved to write really depressing books where nothing good happens. His books also tend to contain a lot of commentary on various issues of the time, and issues today. The Man Who Laughs is a book about a guy, who as his father's punishment, gets a permanent smile carved into his face. Aside from that lovely tidbit, the book contains a lot of commentary on the upper-class and lower-class.
This is an article that discusses Gothic art and architecture. I don't have much to add that the article hasn't. I quite like Gothic architecture though, I'll say that.
This is a documentary talking about Gothic Cathedrals. They are very impressive buildings, I must say. Especially impressive considering when they were built. A lot of math and a lot of time.
This is a video that gives an overhaul of what Gothic architecture is. It serves its purpose as an educational video.
This is a brief video that talks about Gothic architecture. If you wanted to provide a basic and entertaining summary of what this Gothic architecture stuff is about to a classroom full of kids, I would recommend this video.