My overall thoughts:
1) A poor day, but with our batting lineup how surprised should we be? It has gotten to the point where we need to bowl sides out for 150-200 consistently to have a good shot at a first innings lead, but that just isn't a realistic expectation no matter how good your bowling lineup is. Paine losing his way with DRS/field placing towards the end of yesterday looks like it will hurt.
2) Langer has put his stamp on the side in terms of playing style - where Lehmann's sides often tried to hit bowlers out of the attack, Langer's sides try and grind them down. The problem was that 1) we didn't rotate the strike effectively like Pujara did yesterday and 2) a few of our batsmen played poor shots. As such, we may not have collapsed over minutes, instead eroding over hours, but the end effect was still similar.
3) India generally bowled tight, disciplined lines. Against such a unit it is important to rotate the strike, not only to get their fielders to wear themselves out by chasing the ball, but also to disrupt their bowlers rhythm against left-right hand combinations, and also give their captain something to think about RE field placings. We didn't do that though, so their bowlers were able to settle into a comfortable rhythm and Kohli didn't really have to change that much.
western royboy suggested that this was down to 20/20 cricket and its emphasis on boundary-hitting rather than running between the wickets (unlike ODI's) and given CA's apparent deference towards that format I have to agree.
4) The conditions are hard to read because IMO neither side has batted particularly well. My impression yesterday is that after some early movement with the new ball, the pitch was largely blameless and could yield plenty of runs provided that batsmen got set, rotated the strike intelligently and didn't play silly shots. Today there was a bit more spin but nothing extravagant. Again, Travis Head showed that patient, intelligent batting could get results.
5) Beyond a second innings miracle, Shaun Marsh is surely on his last legs. He did well in the Shield but his Test form has been shocking and Ashwin seems to have his number. The question is who replaces him. Wade and Maxwell are the most obvious options. The former is in better Shield form and plays pace more effectively but the latter is a right-hander (thus making it harder for Ashwin to dismiss him on non-dustbowls) who plays spin better. Wade is more likely to be selected.
6) I'm worried about Finch's technique when the ball is moving. He will do OK opening in the UAE and facing a lot of spin bowling but I'm not so convinced he can do the job here. Maybe give him one more Test match before making a decision.