2005 Rinker 320 - Mercruiser 5.0L MPI - SmartCraft VesselView Mobile - Installation

Just bought a 2005 Rinker 320 EC with twin Mercruiser 5.0L MPI engines (smartcraft capable).

Currently I have analog gauges, throttle etc. and really not happy with the analog gauges (fuel, RPMs).

I would like to start upgrading my electronics and gauges.

I have found the SmartCraft connector on both engines with a weather cap.

It appears I need to add a junction box and cables from the engine to the junction box.


I see there is a wiring harness for SmartCraft Vessel View device and DTS throttle which has a lot of connectors.
I dont think I need that harness.

I understand the installation of the Vessel View Mobile module to the junction box,
but not sure of the wiring architecture from the engine to the junction box.

I currently want to keep it simple, but later may consider the VesselView link which will tap into the junction box.
1. do I only need a cable Harness from the engines to the junction box?   (straight, no additional connectors).
If so what wiring harness\cable is it (product number or serial number) ?

2. If I just add the Vessel View Mobile?  
What functions are not available to me if I don't have digital fuel, DTS throttle etc?

Thanks in Advance!