I have searched documentation but cant find any example and wonder.
1) Is it possible to use Azure Storage (Blob or File) to store assets files like pdf, docx i.e files that editor could upload and reference?
If its possible:
1.1) Is it possible to structure uploaded files in "catalogues" in Epi edit mode. As I know Blob storage in Azure is kind of a flat structure but maybe you could use Container as a catalogue or?
1.2) Is it possible to use ACLs for files so you can filter files based on logged in user/editor?
Answer for you first question is yes you can upload the blobs in Azure storage
but for other questions I think out-of-the-box is not available.
1. Yes, you can just install EPiServer.Azure, configure Azure blob storage and everything will be transparent to the editors. (Actually if you are using the disk-based blob provider the physical folder structure is quite "flat" as well. the logical structure is "abstracted"
2.Yes, ACL can be set to media