I am using mininum latency and having no problems in games nor with music.
I don't know how much that ASIO buffer setting matters and maybe it is used only when using its own ASIO driver (TUSBaudio). I have it at the minimum, 64 samples, and no problems so far with games and music.
WASAPI and ASIO4All have their own buffers settings so if you use any of them you can try to lower them as much as you can (and it depends on your goal); in my opinion it doesn't matter much if you are just going to listen to music (I personally use WASAPI exclusive for bitstreaming and indeed low latencies are not that important).
About the rate. If you are on Windows then all the audio passes through the Windows audio system (usually DS API unsless otherwise selected and probably WASAPI shared) and it will resample any audio source to the sample rate you choice in the advanced system audio settings. So if you are going to listen to 44.1kHz use 44.1kHz and 32bit (I am not sure but probably 16bit and 24bit audio files will be just padded into 32bit without any dithering) because it has been tested that Windows DS resamper is not that good (I don't remember the source, probably by archimag's blog).
If you are going to use ASIO or WASAPI exclusive then that setting doesn't matter because the audio stream will be passed directly to the DAC (a perfect bitstreaming) and it will do its own processing.
About the led I can't help, maybe unsolder it? I have the board in a printed case and it is hidden so it doesn't bother me