About the other match, tsonga's performance is unbelievable, he has beaten berdych and kei, which are all great players, I hope he can beat wawrinka.
IMO, Djokovic should have a very good shot of winning the French. Past historical statistics aren't always the best indicator - you'd need to take into account weather, injury etc. - but Djokovic's playstyle outdoes that of Murray's. They are both very strong defensive players - but Djokovic has both the better defense on both wings and the better offence on the backhand side.
As to Nadal, he's a fading force, I'll always support him but the fact of the matter is that his injuries have hampered his playstyle (can't produce the same topspin and raw power) and age is catching up to him at last. Not being able to win a French is the beginning of the end for him IMO.