No child support since oct 2010

We have a court order stating my ex pay $581 monthly I have given copies of that to state child support enforcement in IL .. my ex says he will soon be getting disability & so will our two children, i have talked to disability they say that is true..

Also he says that his tax's were taken
so my questions are:
1) will i get notice if I am receiving back child support from his tax's?
2) once the disability (SSD) starts is that to cover his child support or is it separate?
3) I applied for child support help back in Sept 2010 why is it taking so long?
I may also get back pay from disability for the children but form my understanding that doesn't cover any of his back support due.. is this true?