1. I used action=editforumfilters. When will I notice the changes? I logged out and logged back in, but I still seem to be getting the same forums I was getting before; e.g., I don't need to see things headed "Japan."
If you are talking about forums appearing on the front page then you won't see any changes as the front page is not affected. The forum filters only apply when you browse posts from the forum menu at the top of the page (either Hot, Recent or Active).
2. In the news section, is there a way to not see the iOS entries?
Again if you are talking about the front page module, there is unfortunately no way of not seeing them. I have removed the module on the front page and rely on subscriptions to get just the BGG news posts.