I'll do a review about the Pulse 3D vs Astro A40 at least, not sure if that'll help. But I still believe the MDR-7506 connected to the DualSense will be a much superior solution to both.
I think the Pulse 3D is a reskinned PS Platinum with minor tweak, so being cheaper actually makes sense. I hoped that Pulse 3D will have the rumble/haptic feedback to be a true successor to PS3's Pulse headset that had rumble with explosions and so:
There is no indication in the Pulse 3D that'll support further signals above basic 2.0 stereo like 5.1/7.1. But I think it'll do as some use them for PC as well.
Yes, and it's most likely a reskinned Platinum with minor tweaks.