V_S,
CSR nailed it. I am amazed at your energy. I honestly don't think I can write in so much detail. It requires a certain amont of passion, which will give you the required energy.
And yes, Raja understands the nuances of each area as only he can. People can also check out songs like 'jakkamma' (Solla Marandha Kadhai) and 'ennada paandi' ("Valmiki") to understand how wonderfully he captures the spirit of Madras. It is not just any other 'gana' song. This man and his music are magical.