The schools do get extra money for military kids. There is a form that the school sends home each year for the parent to sign that says they do in fact work on government land (base/post). It isn't just schools that have a high population of mil kids it is any school with mil kids. Our school must make a good amount of extra money because we don't have to provide any school supplies at all.
I know nothing about IEPs or schools making more money for kids that have them. My inclination is to say no which is why it seems to be so difficult for kids to get the services that they need.
I hope you find the answers you need. The base/post usually has a school liaison to help parents with school issues. I have never used one but have heard them mentioned.
Mom to DS1, DD, DS2, DS3