I am not from Bangalore but we are using these kinds of stbs from 2003 in Chennai.
a. Is both Analog and Digital TV is broadcast on the same cable in Bangalore?
b. Can a satellite receiver be used as a cable stb? If yes, what special settings to pay attention to?
NO, but might be possible if you can change the tuner, software etc., which ends as a new stb. Moreover Cable stbs use QAM for modulation. A software change is need for that.