I can't speak for the disability pay, because depending on the circumstances of that pay it could be subject to lien for other debt, such as back child support. But generally, SSDI is exempt from such debt. However, your pension most likely will not be exempt regardless of your disability status now, since it's "back" child support that was to be paid when you were in fact, working and/or able to work.
"Once I am labeled disabled, I can write off all of my student loans."
This isn't something that happens automatically. I don't know the details myself, but you'll have to do some paperwork and submit proof of your status before those loans are forgiven. But thankfully due to a change in the tax law for 2018, that forgiven amount will NOT be taxable to you, whereas in the past it would have been.
