INSEAD

Congrats on INSEAD!

1) INSEAD is a consulting school with 50%+ in consulting. Per their employment report only 28 people went into IB. 28 is a pretty small number given how big their MBA classes are. 14 of these 28 went into IB as Associate/Senior Associate while 7 as Managers/Consultant and 7 as Principals and above. The 14 that went in at higher level had previous experience while the other 14 were potentially new entrants. That is even a smaller #! Also where do you want to go for IB? In Europe/Asia/US? Note that INSEAD did not send anyone to IB in the U.S. - if that's what you are aiming for. 
One thing that is important to land an IB job is getting an internship. Good thing that Jan intake gives you the option of pursing an internship in the summer. 

You also get the opportunity of doing an exchange program at Wharton and Kellogg. Remember - exchange program at Wharton is far more competitive than kellogg. This could be your chance to network. It is a bidding process at INSEAD (everyone is allocated the same amount of points). So you kind of have to go to the worse classes at Wharton if you really want to have a good chance. 

2) Only in extreme circumstances. Usually the college is pretty strict on this. Down Payments are also a way for the college to have higher yield numbers - because they know that you are waiting on other decisions. So unless you have a very good reason to why they should extend your down payment - don't even try. Keep in mind that the 27th date for Wharton is just an interview date. It is in no means a decision date for admittance. Are you willing to shoot yourself in the foot for an interview invite? What I have seen others do is pay the down payment and still interview with other colleges. If you get admitted - well time to decide if you are willing to let go of the down payment. If you do not get admitted - well you are in the same boat as before and INSEAD is your only option. Know that the down payment is a small amount as compared to what you will be paying, regardless it is still something.

In general - if you wanted IB you should have tried for LBS in the Europe market and not INSEAD. Going to INSEAD is more so like aiming for consulting only and that's what people go for. Some people end up pursing something else and deter away from consulting. A very small amount come through with a specific goal of IB at INSEAD.

If I am in your shoes I have two options I will think about:

1) Attend INSEAD and try to go for IB. If you fail - go for a backup plan (ALWAYS HAVE BACKUP PLAN) in corporate sector or consulting and you will definitely land something from there.

2) If money is not a problem - pay down payment at INSEAD - interview for Wharton/other schools - and see what they come through with. If they come through with admittance than think about letting go of downpayment or not. 

*Remember* by the time you start at INSEAD and finish - you will just be finishing up your first semester/term at Wharton/other schools. Thats 1.5 years of lead time you will have of working.