I can say the DAC the NOTE uses was superior (initially) to the Galaxy S.
However the DAC on the SGS had open sources and VooDoo gave incredible performance because Samsung made a sloppy effort first time.

I can say the DAC/IEM is not great, but it definitely is "acceptable". Putting on Beats headphones, the quality doesn't improve too much but its still a nice experience. Anyone with qualms with the DAC/IEM performance would be an Audiophile, in which case I would tell them most smartphone audios are disappointing, only a dedicated media player would suffice.

The SGNOTE supports Wifi abgn + Direct. This means support for the 2.4 and 5GHz ranges. I haven't had any issues so far.
I've just googled it, and there are quite a few Gnex owners having problems with the 5GHz band --cheap part or crappy driver, or both.