Subtitles take up very little room. And sometimes, they [usually the English ones] are needed too. Otherwise, how will you know what the aliens are saying;)
As regards audio, the advice in this thread is correct. Not everyone can use DTS, which is very high quality sound, but which takes up lots of room that you might think can be better used by the video. It's a trade off. If you have an AV amplifier and surround speakers and ears like a bat, then the sound might be more important than top notch video. Only you can decide.
Two channel audio is normally reserved for Director's Comments and the like. Riveting stuff that most are happy to discard.
In the example you show, it looks as if there's some duplication - maybe the program you were using became confused. I suspect there are only two files, not four.