Yeah, I had mine setup like that too but for some reason, I had to unplug it and plug it back in too often. I have the chromecast audio now and it's so much better. Way more reliable and the music starts much faster when I cast to it.
I like a empty home screen. I use Nova to add 2 folders with a very faint circle as the icon for my most used apps and the home button opens the app drawer.
Yeah, the multi room support is said to be coming later but it would be really nice if it applies to the regular chromecast as well and not just chromecast audio. I guess we'll just have to wait and see.
I have that setup and it works about half the time. The other half I have to unplug the chromecast from the adaptor and plug it back in to make it work. Not sure if that's typical but that's my experience. I went ahead and ordered a chromecast audio. No more worries once it gets here!