Network recommendations for best IPv6 compatibility settings, passthrough, in-home game streaming

Dear networking pros,

I could really use your assistance. I have a Pace 5286ac connected to my tp-link Archer C9 via DMZplus. My home network generally has about 10-15 devices connected at a time. 

1. I want to improve my home network's IPv6 compatibility. Main issues: right now, my ICMP is filtered and neither ipv4 nor ipv6 show hostnames. Which firewall rules/advanced settings can I implement to achieve this?

2. What (if any) advantages are there to using IP passthrough on a BGW210-700 over DMZplus on a Pace 5286ac? Which modem is best for sending my connection to a modern 802.11ac wifi router without interference? 

3. I like to stream my PC games via Steam's in-home streaming function. How can I achieve the lowest possible network latency in my setup? I know to use ethernet on it all. 

Thanks!