5.6-2 May I use a quotation in a work that has been put online? For example, an image or a music excerpt on my homepage?

Yes, pursuant to the law, it is irrelevant in which medium (book, pictorial, homepage, app, film,…) a quotation is used. However, it is decisive that the quotation has an explanatory, informational or illustrative function, is covered in the scope of the purpose of the quote, is disclosed as a quote, and the source is specified (Art. 25 para. 2 CopA).