Having visited the US (with, or without, disclosing your dream of studying at the MIT) and RETURNED home on time will weigh more than being paid by cheque, or whatever other method. Answer the questions truthfully, this is all there is to it.
Also, try to not be so anxious about it, you might end up looking suspicious. Breathe and think about the positives of your visit: what do you want to see, why another trip to the US now, how excited you are to see A, B, and C, and then to return home and tell your friends about it - like that, but with your own voice. You did it before, you can do it again.