MSD = Multiple Security Deposit. You can put up a maximum of 7MSD's to buy down your Money Factor (MF) - which basically is your interest. One MSD equals one monthly payment rounded up to the nearest 100 (in your case: $900, so 7 x 900 = $6,300). One MSD reduces the MF by 0.0007. MSD's are fully refundable upon lease end. It is not a good idea to put money down on a lease, if you crash the vehicle your money down is lost. It's not possible to judge your deal based on the info you provided; you need to negotiate sale price and money factor as other variables are "set" like residual once you decided upon your term and mileage.
http://www.ridewithg.com/index.php/2...-auto-leasing/
This website also has lease rates per brand and a handy lease calculator.