I think, if habbo closes, other FREE retros will get more users. Because, it's better than having a limit on a game like Habbo. So, other little Retros might get more bigger in my opinion.
You can donwnload "get paint . net" (withou quotation marks). Open it and click File>Open and look for the furni image and you should be able to edit the furni. After that, you can code it into the game.
For help coding it into the game, search on Youtube, "How to add custom furni into r63 /...