There is most likely an overlap on what you can get from the OBD port, but generally speaking the API will provide more high level info e.g driving status, mileage, live location - and the OBD port will provide more low level data e.g. detailed battery stats from the BMS, energy usage, etc.
Not at all.
Lemmy is overwhelmingly militantly anti-Tesla, which is understandable considering who owns it, but it does mean that users tend to interpret any neutral or factual statements (basically anything that is not outright criticism) as having a pro-Tesla bias.
In this case, all I am stating is the fact that this specific change currently only affects corporate users. That could of course change in the future.
There is a rich history of cloud based data providers pulling the rug from under users with no warning. Look at what happened to Nest users when Google took over.