what you told is correct but dont forget if upper order dont perform better in india then i think we can see south africa favorite in odd for some time and you should be knowing that most of the players who are playing in SA have played in IPL games in this pitches and faced indian spinners so you cannot underestimate SA.
Yes today India can win easily if they play as per their potential. It a good opportunity to win some money today.
Indian players are quite strong when they play at home and pitches may be mostly spin supporting. All these are made as per Indian players favour so technically India should win this series but SA if they play their natural game then for India it will be quite challenging. I will try to bet during live match than now.