Student Loan Rehabiliation

I have defaulted on my student loans and am getting prepared for the
rehabilitation program.  I'm wondering what experiences people have
had with this program.

Have you been able to have all your derogatory information removed
from your credit reports from all your student loans once you have
successfully completed the program?  Or does the negative information
(ie. lates, defult status) stay on the report?

Have you been able to negotiate any of the debt down or any of the
exorbiant collection fees they charge down?