My Fairphone 3 has a headphone jack and is running the most recent build of LineageOS, so yeah.

I’d consider that if they added a second USB port, but no. Why would anyone want to use headphones while their phone is plugged in?

Yes, the top-level domain is still just a domain. I’m not aware of any public Internet services which are reachable from a TLD directly, and it’s strongly discouraged by ICANN, but there isn’t any technical limitation preventing e.g. someone at Verisign from setting up example@com.

always remember to tip your server