SP1000 is not a MQA renderer (when used as external USB DAC), that is why Audirvana shows "No MQA device detected". It means SP1000 cannot fully unfold MQA encoded file.
You can play with MQA Renderer/Decoder setting. The first unfold will be done by software - Audirvana, but SP1000 cannot unfold the file to its original.
I think SP1000 can fully unfold the MQA encoded file if you have it stored on the device (I am not sure about Tidal streaming MQA file) - correct me if I am wrong.
See my screenshot below:
Original file is 24bit 352.8kHz (see top right corner)
On the left top corner you can see that Audirvana unfold it to 24bit 88.2kHz (Audirvana did first unfold, SP1000 cannot unfold it to original 24/352.8)
Regarding second question - yes DoP settings are related with Native DSD Capability. I have got it set to DSD over PCM standard 1.1.