Yes, you definitely want to research pay for delete options for the medical collections. You want those off of your reports once they are paid. Also, I don't know much about this process (assuming it is still valid) but google "Mod Cut hipaa process." That will give you some advice on how to have medical collections removed from your report. But it only works if you haven't paid them.
That particular site name is not allowed to be posted. Also the HIPAA process will only work once the OC has been fully paid.
MarineVietVet, myFICO moderator
Starting Score: ~500 (12/01/2008)
You have several issues in your post. You mention you would like a lower payment, is the payment itself too high or is it too high with all the other debt you have accumulated on your cc's? I ask this because sometimes its really tough to figure out a budget if all you feel is overwhelmed when you look at the payments.
You might want to start with writing down your current expenditures - write down everything including any trips to fast food places and other budget busters. Then take those amounts and total them for the week and the month (you will need your bank statement and cc statement to do this). Once you do this you will see where all the little bits are adding up to fairly large amounts (like visits to fast food restaurants or the grocery store). You can then re-prioritize your expenses so that you can put the money in savings rather than give it to Micky D's or someone similar.
Once you get the budget under control, you can look around the house to sell whatever is not nailed down. Put that money in savings in a CU.
Then go over to the credit rebuilding forum here for advice on reducing your utilization and getting rid of the collections via pfd or other methods.
By having the savings in the bank/CU, your decision making process will become more clear. IME, having $$ in the bank/savings makes everything more clear! 
By then, you can see if you have enough in savings so that you can either refi your vehicle with the same CU where you have established your now rapidly building savings account or sell it and pay the difference. In any event, the CU will work with you once they see that you have an established pattern of savings. Also, your score will probably have improved if you have paid down your cc debt so your utiliztion is low.
IMO, I would work on the savings and you can always boost the score rapidly by making a lump sum payoff to the cc's with that healthy savings. (Allow 30 to 60 days for it to reflect in your score). The rebuilding section has lots more detail on this, search utilization and snowball method.