Hai! I'm no expert but here's my shot 
- Closed accounts with balance still factored in your utilization calculation. 75% is from adding all your balances (except the AMEX) and divide that over your total credit limit + 924 installment.
- I think the TU FICO score you buy from this site include the AMEX charge card balance into util calculation, but with newer FICO scoring model, charge card balance aren't included in calculation.
- I also think it is better to pay off/down the account with highest APR first as this will save you a little money over time.
Starting Score (08/11/11): TU08: 643
If you are serious about your financial future then you probably shouldn't be serious about watching your day-to-day FICO scores. (DISCLAIMER: I like to do it, as do many others here (I think it's often just sport/hobby)), but it really isn't a proper long-term strategy.
Unless you are trying to tactically raise your score for a specific upcoming loan app, there's no reason (IMHO) to do anything but attack the highest rate balances first.
If you're about to buy a car or house, without having payed all that other stuff off, then ignore that advice and just keep in mind your overall, and per-tradeline utilization %s, as well as the number of accounts with balances. Nobody here really knows how to balance those three factors. I recommend using 'the force'. Given the mysteries of the FICO algorithm, that's about the best weapon I could find.
Whenever I'm shooting for a score, I look for any low balance cards that I can quickly knock down to zero. At the same time, (and maybe even with a bit more importance) I try to get all revolving tradelines below 75% utilization. Then I try to focus on getting down to ~3 tradelines with balances (maybe 4 given the number of accounts that you have). Finally, I try to keep the per-tradeline utilization percentages of these remaining balances all the same. That way, they will all hit any hypothetical per-tradeline milestones at the same time. In other words, they will all hit 49% per-tradeline utilization around the same time, etc.
DISCLAIMER #2: This is just my formula and I have no scientific reason to believe that it is any better than randomly allocating your payments across your current balances. I used the force to come up with it along with the old "what would I do" method. That 's just me saying to myself..."if I was a FICO algorithm, what would I like to see?"
And yea, there is one last factor... for some reason, this formula gives me the greatest sense of 'perceived' progress. This should not be underestimated as a motivating force. So whatever you decide, just convince yourself that you'e doing it the right way and just get it done.
Having an incredibly manageable amount of debt (and a decent score to boot) is greaty satisfying. I can only imagine what it is like to be fully debt free. With a little work, we will hopefully all find out.
Warning...^^^^^^...this is the kind of cheesy inspirational crap that starts coming out of my fingers when I make long posts. But I mean every word of it, just no quite that cheesy. 
Good luck
DISCLAIMER #3: I am no credit expert, but I do play one here on the forums from time to time.