Have you double checked if you had some kind of Wiring Failure in your Here3 module? I have never saw the CAN errors that appear in your log, it seems like it lost CAN connection and then tried several times to restablish communication with several different rates.
Personaly, I think it is always good to have GPS and Compass redundancy.
These messages are written by various drivers inside ardupilot and are not necessarily related to params. Open a log in the tool I sent you the link and plot any data and look for the messages button, it will open a new window inside it with some messages and you can see them appearing as you pass the mouse on the graph.
I would left the I2C strip away from the power source lines in order to avoid any kind of power noise on the data lines. It’s not a good practice at all to mix power and data wirings.
The ones I saw in the log that recorded the flight in which your drone failed I have never saw in normal operation in healthy systems. For me it seems like trying to begin a communication but failing all the time, but I could be wrong about it.
I don’t think so. But you can use UAVCAN tab on Mission Planner in order to check communication with your module and check if you are running the latest firmware available on it.