I don't get why AR/FL work so inconsistently. I have never been able to get either my 1.06 AR (first edition) or 1.06b FL (last pre-Wii edition) to boot Euro games. I also can't get the AR to boot homebrew on the Wii while some people can't. Some can't even get FL to boot Japanese games, while I can. Mods fixed all those problems.
As for Japanese games, you do not need a Japanese formatted card except for an isolated few cases, such as Mr. Driller Drill Land (you'd also have to actually switch your GC into Japanese mode). The text in many games will be screwed up since it will be reading the wrong font information, but they will work and save otherwise.