Technically, you don’t have to run Ethernet. You can buy an access point, connect it to your existing wifi network and plug your bridge into the access point. I may be confusing the use of “hub” in your connection or maybe we’re referring to one in the same thing.
I ran the above setup with the bridge on my Directstream Junior, played flawlessly, sounded great with Tidal MQA.
JRiver and Roon, do the same thing, with minor differences. Both will allow you to manage your music library, local to the source device or add external target media. JRiver seemed to be more verbose in the configuration capabilities, but also “buggy” and crashed periodically.
The interface skins couldn’t be more different, as you stated regarding Roon being more “Apple like”, which is quite true. Roon discovered all of my music album art. JRiver, it was a manual labor of love to repopulate the albums with the appropriate image art. It’s been about 1.5 years since I’ve used JRiver, but I believe you have to buy their app, to remotely control your music library. Roon, I don’t believe you do. I recall the JRiver media app crashing periodically, as well.
The PSAudio integration, with Roon, was flawless. I didn’t run Tidal through JRiver, as comparing the two skins and interface is Apples to Oranges. And from recollection, at that point I was done monkeying around with JRiver’s media center. Via Roon, Tidal worked well.
JRiver is what happens when developers write a piece of software to address sound quality on a laptop. Roon is what happens when audiophiles hire developers to bring their creation into existence. My point, if you like tinkering and having a multitude of library/music configuration options, JRiver is a suitable partner. If you want to plug and play, Roon will be a more appropriate route, but you don’t need both.
I’m open to being wrong, but I do believe you need the bridge II network card for MQA support. I believe this is where the software/logic resides for uncompressing MQA on the PS Audio products. Though, if you’re seeing “MQA” appear on readout from the DAC, maybe it doesn’t?
I won’t comment on the AC circuit question, as that’s above my pay grade. Though, I was always under the impression you use the same circuit for your gear. As doing otherwise can create audible AC hum and various other electrical audible disparities.