The bankruptcy itself will hurt your credit score. If you do not plan on keeping the house(s), they can be included in the bankrupcty. It will effect your score no matter what you do unless you can get the lender to do a short sale that includes an agreement that it will be for full and complete satisfaction of the note. Some states also have deficiency statutes that forgive the difference in the balance owed on your loan versus what the house is worth/or sells for. But there are tax implications there. It might look better down the road when someone is looking at your credit report and sees you didn't let your house go into foreclosure (current up until bk filing), but score wise, little to no difference. The mortgage was discharged through bk.
The creditors for your auto loans do not have to let you keep the cars. That's true. But most people will tell you that as long as they stayed current on their payments, their cars were not repossed. You don't necessarily have to reaffirm to keep your cars or even your house. If you reaffirm and later can no longer make your payments, you will have FRESH derogs after your bankruptcy and you DO NOT want this. If you do not reaffirm and find yourself not able to make the payments, you can walk away and not worry about it because they were already included in your bk. Only reason most people reaffirm is for "security" that the creditor will not come after the property. Which in majority of cases they don't, whether you reaffirm or not, as long as you make your payments. So as gadixie said, be sure you are confident you can make the payments on the cars if you do reaffirm them.
