Firstly, 1000/220 is the business package, if you are residential its 1000/110 and sold as 900/100.
LAN traffic does not pass over the router (the ethernet ports are on a switch built-in to the router, only traffic needing to pass to the WAN or the IP address of the router itself gets passed from that switch into the routers internal ethernet port) and any cable CAT5 or better handles Gigabit fine unless its defective.
Where the slowdowns occur is both in the CPU usage for the PPP connection to the ISP and the NAT (network address translation) that has to convert from multiple different LAN clients to a single WAN IP and keep track of where to send each response. The NAT part gets exponentially more CPU intensive when you have QoS enabled, but its possible that is not necessary on such a fast connection.
As you've already ordered the service anyway, there's no point worrying about it yet. Just do some tests one its live.