Roon: is it just a pretty face for browsing music?

No it's a bit more than a really nice interface... it does give you pretty much full control over your sound settings (incl. upsampling, filters, etc.). Even without any DSP active, Roon does sound better than for example Mconnect with my PS Audio DirectStream Sr (with bridge II).

Also, you don't need to have your Roon core computer connected to the end-point, but it needs to be on the same network. I have my Mac in my office and my DirectStream in the basement. No direct connection at all... the Mac is connected to my network wirelessly and the DSS is wired directly to the router.

Mostly, yes. But not just pretty -- functional for those who want to find things in Tidal or Qobuz (which are badly indexed for classical music) or who want to find things in their own local libraries and who haven't made sure they are tagged well.

So I’d have to have my iMac which is connected via wireless with the Roon running on it and then I can have my Bluesound player which is hardwired in another room and this would work?

As long as they are on the same network it should work. You need a good robust wireless or you might get occasional drops. 

BlueOS is definitely the best free interface I've used you should definitely give Roon a trial if you are finding it lacking.

Upsampling makes it more than just a browser and I did find the sound quality to be superior versus running the Lumin app on my Teac NT-505 even with the upsampling feature turned off.

Pretty sure I have a free 30 day trial code that came with my yearly subscription you're welcome to it if you want.