General Credit Repair

So here's the deal...I was an idiot when I was in college, and poor when I was in grad school. For a while, I was poor after grad school. There are several things on my credit that are really hurting my score and I want to fix them.

1) Defaulted student loan
I consolidated my loan through Nelnet, and was told that my current deferral would continue. It did not. In 9/06 it defaulted. I have since rehabed the loan and am current on payments through ACS. There are now 2 Nelnet entries on my credit report for about $8K each. Is there anything I can do to get them off now that I am making payments and am in good standing?

2) Medical Bills
I had no insurance, so of course I got pneumonia. I went to the emergency room in 10/05 where I was promptly charged $3,700 for a 3 hours stay, 2 nebulizers, and a can of albuterol. Awesome. At the time, the amount may as well have been $3,700,000 because I didn't have any money. Now I do. Should I contact the collection agency to make payments or should I wait another 3.5 years for the debt to drop off my report?

Notes:
Every other debt I have now is current - mortgage, car payment, my one single credit card with $1500 limit. I know I should probably have more credit so that my score can go up more, but I can't get the card because of my credit. My score is around 660, and I can only assume it is rising...I mean, I'm paying things like I should have always done.

What should my steps be to clean up and build my credit?

I appreciate any help you can offer. I can't wait to have a credit score above 700...as low as that really is, it's still a pipe dream for me.