There was a History Channel (or Discovery Channel) show a couple years back that showed that the Japanese were not far from completing a nuclear device that they planned on using in the US on a date that turned out to be only weeks after when they got bombed themselves. Even after we used two of the a-bombs, they still didn't want to surrender. After all, it took TWO bombs to somewhat convince them when any reasonable person would have thought one was enough. I've seen the pictures; it would have convinced me.
Not really. Some Japanese scientists knew what had hit them, and had suggested the idea earler in the war. But the Japanese military never took it seriously or undertook a project to build one. After Hiroshima there was some talk of putting together a project to build one, but there was no industrial capacity to do so. Consider the time and effort the USA put into the Manhattan Project. There was no possible way they could start at that point and do so. Additionally they had no unranium to process anyway, since their only source was Manchuria, and we had them blockaded.
Another myth is that Germany was seriously pursuing the bomb. There is a little more truth to that, but the Germans were experimenting with heavy water. In other words they were looking at fusion, not fission. Since you can't have a hydrogen bomb with an atomic bomb first, they were barking up the wrong tree. In any case they never got much in the way of resources because Hitler distrusted "damned Jewish physics".