Settling CITI bank credit card debt

Hi everyone, I racked up ~37k in credit card debt back in early 2009, and another 5k in fees (approximate numbers). I made about 2 payments on the debt in march and april of 2009 - the amounts were ~$700 each. And then I stopped paying/answering unknown phonecalls alltogether.

A year later (April 2010), I received a letter from an atterney (it said "advertisement" on the letter), that went something like:
-Recent court records indicate that a lawsuit has been filed against you by the credit card / zwicker and associates
-We will represent you
-Get your initial consultation for just $150!

I called up Zwicker and Associates immediately, and spun some bs bout how i was out of the country, im all about paying my bills, id love to settle, etc.

They immediately offered a settlement @ 30% of the balance, to be paid in a lump sum, in 3 weeks (supposedly, CITI only gives this "deal" in may ONLY).

~may 15th, i get a call from zwicker, and they wanted to set up a checking account. And i told them - no point, I don't have the money yet, only have 1/3, call me back at the end of the month.

~today, i finally answered the phone, they immediately put a supervisor (or manager? a step above the regular phone-worker-ant), and I told him that yea.... don't have 12.6k you are looking for, is there any way you can lower the balance... may allow me to make several payments? The manager told me that he can offer 10.5k (25% of the balance), but it has to be a lump sum payment, at the end of this month. I, once again, told him i can't do that, is there way he can allow me to maybe make 3 payments... etc.

End result - he agreed on 2 payments, one is on May 30, $6k , the other one is on june 28th - 4.5k. Unfortunately, I was DUMB enough to give them my checking account info without
1) seeing the actual letter, stating that they WILL settle with me, and after the two payments, they will leave me alone
2) Didn't even ask about how my credit score will be affected. According to this site:
"13. Negotiate a "Pay for delete" or "Paid in full" status
When creditors agree to accept less than the amount you owe, they'll report your account status to the credit bureaus. In most cases, your credit report will reflect a "Settled" or "Paid as agreed" status, which has a negative impact on your credit score.

To avoid getting a credit hit, negotiate a "Pay for delete" agreement with your creditors so that your entire account detail is removed from the credit report. Alternatively, you may request creditors to update your account status as "Paid in full". Once the creditors agree to what you've requested, let them provide you with a written agreement of the same."



My questions are:
1) Do ya'll think I could get my balance lowered even more?
2) Should I call back, and tell them that I need to see the letter first
3) Do ya'll think I could get them to mark my credit report as "pay for delete" or "paid in full" ?

Thank you everyone in advance for your comments and help.