Car connects free for itself, and loads navigation, traffic, location on app etc. If you want a wifi hotspot, thats $300 a year from ATT network 2ith 22GB fast speed per month.
No, GPS Shows a red circle & Line if car is far in basements or in downtown. No Traffic Data if no mobile coverage (although no symbols to show how much mobile coverage it has). App shows only last known location (& gas level, odometer, tyre pressure etc) from last point in time connected. Remote start & doors lock/unlock will not work if car is not connected.
Source: my car.