Yes, the Wetsounds EQ is a must have. Besides being loaded with features and making zone control on the fly so convenient, the added preamp voltage will help your system. Also, check out the new Wetsounds EQ billet underdash bracket that also houses the WS Bluetooth.
I think the only tricky part about the system scenario is getting the six tower speakers balanced on the front to rear channels given that the load is not symmetrical. They'll manage. Just emphasize that point.
And place a great deal of importance on the sub enclosure build execution.
And I agree with upsizing to the 12-inch sub. If you have the space, the larger sub won't need to work as hard and that means cleaner bass, even if your not a basshead.