Bankruptcy is an all-or-nothing proposition. That is to say, you don't file bankruptcy on any particular debt, you file bankruptcy on all the debts you owe at the point in time that you are filing. You may reaffirm on certain secured debts, but for the most part you may not pick and choose the debts you keep and the debts that are discharged. If you must pick and choose, there are other options available, such as Chapter 128.
A credit score is a number representing the creditworthiness of a person or the likelihood of a person will pay his or her debts. The scredit score is primarily based on statistical data from the three credit bureaus. Using the credit scores, lenders determine who qualifies for a loan, the interest rate and credit limit. FICO (The Fair Issac Corporation) is a publicly traded corporation and is the most widely used credit score model used in the U.S.