No it's not correct. I would correct it for you but honestly I'm not sure what you are trying to say. The Cure/Joy division stuff? I'm sure this is maybe a product or something but I don't know.

I'd say yes, it is. Though, articles in English-language band names is a whole topic in itself! Sometimes it's hard to judge when to drop the article. I agree with Jerry - I'd certainly drop the article here (то есть, вроде на "I went to see The Clash" против "I found a great old Clash T-shirt")

I was at the flea market and found some Cure/Joy division stuff. I should send it to you!

Yes products like t-shirts, books, posters and etc .