For CR, I suggest that you go and read the whole book, no compromise here. Or, you can also get hold of Kaplan premiere, that's also a good book to consider. I personally prefer Kaplan Premiere over CR bible - short and simple !!
Coming to RC : considering number of pages in
MGMAT RC, I personally think its a wastage of time. The source of difficulty is not with the passage, but with the answer choice. So, I believe you have to be extremely brutal while selecting and eliminating an answer choice - then only you can be good at RC.
I see people suggesting to read Economist article, or NYTimes, but personally I dont how does it help. If you go over all the RC passages in verbal and OG, is there any one passage you can take and tell - "I cannot understand anything...". No.. the difficulty lies on two front - patience or your set of minds in exam condition and second your approach.
Cheers !!