Priority: Do NOT give a collector access to your checking account and debit card number EVER. EVER.
You will most likely hear from them that the only payment they will accept is to directly access your checking account or debit card number. That is NOT true. Don't cave in. Tell them that you can pay them $X with a cashiers check or money order. Alternative, is to set a new account specifically for that credit card and only put in the exact payment amount that is agreed upon. This is less desirable though.
Next: Go to annualcreditreport.com. You can view/print your credit report 100% free. This will help you to know what is owed and to whom, and the balance.
Then: Work out a payment arrangement with a collector. Do not send them ONE dollar until your payment arrangement is in writing and in your hands. If the payment arrangement sent to you is incorrect, do not start paying on it. They will most likely tell you that they can't send a payment arrangement in writing. Tell them that you can't send in payments w/o a payment in writing. Don't cave in on this.
If it were me: I would start with the smallest debt as you can get that paid off the quickest. You need that surge of YES! I CAN DO THIS!!!! motivation to stay the course and not let those collectors beat you up.
ALSO, keep this website bookmarked:
Fair Debt Collections Practices Act http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre18.shtm
Vehicle purchase--definitely save cash to buy your next vehicle. Why do you think you will need a car replacement in 1-2 years?
Income--what can you do to earn more income?