Can/should we actively use thoughts as part of mindful awareness?
Mindfulness (sati) does not mean "awareness" or "observation" of objects. 

Mindfulness means to carry or maintain a wise thought or view in the mind.

The original scriptures say: 


  One is mindful to abandon wrong view &amp; to enter &amp; remain in right view: This is one's right mindfulness.
  
  MN 117
  
  
  
  One recollects the Dhamma and thinks it over. Whenever, bhikkhus, a bhikkhu dwelling thus withdrawn recollects that Dhamma and thinks it over, on that occasion the enlightenment factor of mindfulness is aroused by the bhikkhu.
  
  SN 46.3


For example, if the teaching of non-craving &amp; non-unwholesomeness is maintained in the mind using mindfulness, the mind will be clear &amp; quiet. When the mind is clear &amp; quiet, it will naturally become observant of the breathing without any intention to observe the breathing. However, it is not mindfulness observing the breathing. It is consciousness that observes the breathing. All mindfulness does is keep the mind free from distracting thoughts. 

The scriptures (AN 10.58) say all dhamma practises are "governed" by mindfulness. This is the role of mindfulness, namely, to govern practise and keep practise on the right path. Mindfulness does not observe objects. The observing of objects happens automatically because it is the mind's nature to be observant, conscious or aware.