1) You still can only attack one enemy.
2) Some vehicles (like open topped ones; not sure if they are in AtB but they are in SoS) have red defense on flank and/or attacking in close combat - this is what the soft value is for. It still must be used against vehicles.
Thank you for the answer. There are several open-topped vehicles in AtB as well.
So attacking those units with Tellermine could be less efficient than attacking full armored units. Hmm...