Have you tried searching for the communities first? As I understand it from some other posts, if you try to access a remote community via URL through your home instance before it "knows" about it, you'll get the 404 error. Someone (you) on your instance has to make your instance "aware" of the remote community by searching for it first. Then, after your instance is aware of the community and federating it, you can access it via URL as you posted above.
The "collapse" of the government in a parliamentary system means the government no longer commands the confidence of a majority of the (typically) lower house, in this case the House of Representatives. Nothing immediate happens, although the prime minister may (or may not) resign, a "caretaker" government takes over until a new elections are held.
Here, it sounds like one of the four coalition parties has pulled out due to disagreeemnt over immigration, which the coalition parties had never agreed on.