Build a Credit Model

Hello all, here is what I need: Spreadsheet that contains the form of calculation of credit financing operations. Spreadsheet must have the following information and their due formulas of automatic calculation: - Operation Amount (R$) - Tenor - Interest rate - Grace Period (this point is important: I would like to have a spreadsheet that automatically calculates if I include grace period or not, it can calculate how much interest will accrual during this period, etc.) - PMT number (Ex: 1, 2, 3, 4 ....) - Maturity date of the installment (Date) - Amortization (R$`amount) - Interest rate (%) - Special column for calculation of tax on the receipt of installments (tax considered at 14.53%). - Total amount of the installment (principal + interest) These are basically the items that I need. The most important thing is that this "calculator" should work % MAXIMUM automatically where I just need to input some information (as above) and the spreadheet calculates everything. Thank you so much.