Lots of interesting questions Corry, to link all your electrinics you'll want a NMEA200 network, pretty easy to install, the biggest cost will be the Gateway cables. If you're wanting to be able to control the kraken from either garmin units I think you will 2 of them.
Charging lithium batteries from your motor is unchartered waters for me but I suspect you will need a dc/dc charger but I'll leave that to others more knowledgeable.
Edit: maybe only one gateway cable, not thinking to clearly. Still expensive for what it is.