Pablo, first of all thanks for taking on that work. I did not know that the company is not behind the efforts anymore, so thanks for letting me know.
As for your questions:
You should attach the files to the room. You do not need file storage for this, just use a small page that allows you to view all files attached to a room. There exist a couple of these throughout the toolkit, DaveB can point you probably to the best example.
If .LRN is installed, you might copy the files over to the public folder of the community, so on the page where you can see all files attached to the room (cr_item parent_id = room_id) you should have a button "copy" to "select box of all folders in the .LRN communities file-storage". This way you can make files send in chat available in any folder of the community manually and do not have the problem of figuring out what the public folder is.
Language: A lot of language keys in English have been missing. My assumption was that you developed the package in Spanish, which would explain the missing language keys. Otherwise just make sure that you export all language keys before committing.
Hope that helps
