All of those are handled automatically. The only people who have problems are ones who want to configure manually. More importantly, this is no different than IPv4 where have DHCP or manual.

Nearly every ISP uses DHCPv6-PD cause harder for manual configuration. The range is in the DHCP-PD, your router picks a subnet. The WAN address is automatic, and don't care about it cause never see it. Mine is link-local and hadn't known until I checked.