There are, I think, a bunch of different things "Connext Navigation" can mean. The implementation has changed over the past few years, and it depends on the specific Connext screen you have also. On the 23 and 24 model years for XD boats at least, the GPS mapping is really quite nice. Up to date charts with accurate depths, and simple to use. I typically don't define complicated routes or save way points since I'm not much of a fisherman... Navigation using the chart is quite easy though. The system is full featured in terms of routes, waypoints, etc, but it is a bit clunky (though no more than most). The owners' manual does a decent job of describing it. I also have a hand held Garmin and the Wavve app on my phone (so long as I have cell coverage, the Wavve app is much better than the Garmin handheld in my opinion), but I never have need to break them out.
Being new to SW FLA waters, the chart makes picking my way through shallows a piece of cake.
In any case for AOK, there isn't an online resource that I'm aware of, but the owners' manual is a good place to start. Relative to updating the system, I'm sure it's possible. There are some videos on how to do it for waverunners, and I'd bet it's similar (USB drive to a USB port on the back of the Connext). A dealer is probably the best bet in terms of finding a specific answer for your 275.