optical cables and soft/hard subtitles ??``

[BACsader]

For most televisions, the optical out is not meant to be a passthrough for rca audio in from other inputs. It is meant for antenna dolby digital for digital sources. Technically it wouldn't even be 2.1 because rca left right audio is only 2 channel discrete. Your best bet is to just wait and then put money into your receiver and you can just used hdmi for both audio and video. I don't know what you mean when you talk about subtitiles. Is it just for that movie? Isn't that part of the disc and not have anything to do with the 360?
Hope this helps.