These bonuses can be used by adding them to the appropriate matching slot, i.e. support bonus to support slot. In addition, tactical bonuses not only require a hero to be evolved to two stars, but may also require the player to have a particular class in the main slot in order to activate. Evolving support heroes will improve their associated bonus.
While not an ability bonus, players should also keep in mind that their main hero gains 20% of their support heroes' shields, health, and hero ability damage.