I am 2004 MBA of CKGSB. From my expierence there is no time limit for for industrial analysis.
The point is to show your uniqueness. the guys from admission will watch your presentation skill inculding body language, reaction under pressure and so on. keep in mind to be confident at any time without showing off.
As for to what extent, it really depends on yourself since applicants have very different background.
it is for sure that you have to prepare all the material you need. Normally PPT file is a must for presentation but not neccessory to take the notebook with you, either take U-disk or send ppt to admission office is ok.