1. I have 4 years of business development experience - overall 10
years of experience. What is the total score I should aim for to get
admission in Warthon or Harward or Kellog?
800. No seriously, we typically recommend that you surpass at least the lower end of the 80% range of scores of admitted students. In the case of the schools that you mentioned, that's approx: 660.
2. I am getting a score of 590 / 560 in Crack Gmat. Do I conveniently add 100 to confidently say I will be able to score 690 in the actual test. I have not taken Kaplan
or Prionceton yet.
No that's not very accurate at all. We highly recommend taking a PowerPrep exam. It is an actual GMAT exam and therefore tends to give a much more accurate score. You can get a hold of such an exam for free at: http://www.mba.com