Garmin nRoute does not work with NMEA GPS devices; it requires Garmin PVT data. However GPS Gate can take the NMEA and provide a signal nRoute will use.
I think Canada Topo v4 is in the new Garmin mapping format and will not work directly with nRoute. There is a program - MapReverse Converter - which can make it usable though. However, you might want to consider the excellent Ibycus Topo Canada maps as you probably will not require the routing functionality of the Garmin maps.
http://www.ibycus.com/ibycustopo/
nRoute will not support 2 data streams at the same time. I was thinking you could run 2 copies of nRoute but that would require 2 instances of GPS Gate and that is not possible. I think you would need 2 separate laptops to monitor both locations simultaneously.
Terry