Can I connect the Viasat modem into an existing wired network without using its own routing capability. In other words can I turn off DHCP and allow the modem to switch data over its 4 1G ethernet ports and let my router do the IP assignments?
Yes and no. If you turn off DHCP on the modem and use DHCP on the router all devices need to be plugged into the router and only the router WAN port plugged into the modem. That is what you are doing by enabling bridge mode