I would strongly suggest to register your phone number to the National Do Not Call Registry found here. That should lessen the number of calls you get.
It sounds like you've answered your question though, if you're happy with the G3 then I'd say just stick with it. I'm pretty satisfied with mine and plan on keeping it till the next G5 is announced.
I just checked, we have the same settings for the chromecast app and mine works fine. Have you tried disconnecting the chromecast and reconnect it back?
OP, which carrier are you on? I'm using a D850 on AT&T and I don't encounter those issues at all. Try calling your technical support with your carrier to attempt to fix it.