… hi - am I right that the only way/correct way to actually use Chromecast and have desktop information on the TV is to have Chromecast connected to TV via HDMI and the use the digital output from the TV and move on to a DAC?
So it`s Core > Chromecast/Endpoint > TV digital out > DAC > Amp… ?
No, listen to Roon as you always have, and click the Displays button on the volume popup. On your TV, select the Chromecast input in order to see it. Audio and video take independent paths, but are linked.
… ah - so you use a Roonready Bridge/DAC (as always) and Chromecast only takes care of sending the Video/Picture to the TV? That`s great!!!
Building a second system in the living room and I like the thought of having the information displayed on the TV 
Using the updated chromecast firmware (354) for TV screen viewing, a reboot of the my Roon core (imac) and Android TV (Sony) was required before I could get proper functionality.