Just to preface my response, I'm still doing research on this stuff myself -- I'll answer your questions based on my own limited knowledge on the matter.
On sound quality through BT:
It seems like a lot of the complaints levied against bluetooth SQ stem from the compression algorithms used when streaming music from source to receiver. Earlier bluetooth revs (think 1.1 and 2.0) didn't have the bandwidth or the compression algorithms to reproduce music in a way comparable to wired connections. Newer revs (3.0 and 4.0) have better algorithms for dealing with audio -- aptX (wiki) is an example of such an algorithm.
On Dacs:
I'd say the answer is twofold here: first you have compression algorithms feeding in a lossy signal through the dac, so naturally, no matter how good the dac is, the sound coming out would naturally be worse. Additionally (and this is me hypothesizing) the dac itself may be limited by form factor on some of these bluetooth devices. If you consider the fact that manufacturers have to fit the same object on headphones as what can take up its own separate box, it seems more likely that some delta would exist between the performance characteristics of such devices. It seems to follow that the Dacs onboard speakers (or standalone receivers) are probably of better quality on average in comparison to small, portable devices.
I personally think you'd be happy with that solution, just stick to newer bluetooth devices and, of course, read the reviews.