But I think you're missing the point - there's a limit to how many and what kind of field repairs can be made to vehicles before they get returned to the manufacturer for maintenance and an overhaul. There's also a limit on flight hours for aircraft. And we know that those aircraft are making a lot of sorties.
Manufacturers make a lot of money from maintenance contracts and spare parts.

Spares yes, but almost all repairs are done by the military. The contractors do have people on site (field reps) that act as liasons between the contractors and the military people doing the repairs. If the repairs are too great for the field, they send them to a depot - also military. Small arms fire isn't enough to pull the aircraft out of service usually. When McDonell Douglas (now Boeing) started stripping Apaches to remanufacture them into D-models, there were stories about how many bullets they found *still in the aircraft frame*. I think you are over estimating the amount of repair work contractors do.

How is Raytheon going to make money off the Apache that didn't return yesterday? I can't even begin to imagine that connection.

Yes, the military does form the POM off of the need to support two MTWs at the same time. That is used to determine the size of the force they need, then they break that down into further what weapons are necessary.

A lot of that money is spent on supplies that most people don't consider. Stuff like fuel (last figure I saw said the M1 got something like 5 gallons / mile - we have a lot of vehicles burning a LOT of fuel), food, hazard pay, medical supplies, water.

You know where most of that money is going to go? Services. Everything from lawyers to porta-potties. The military contracts people to come in and set stuff up, even for tent cities. It isn't for weapons. Its for support. Do general contractors count as military industry in this instance? When I hear the terms military industry or defense contractors, I (and I'm willing to bet most people) think of the Lockheed Martins, Northrop Grummans and Boeings.

That $75B is a SWAG - it is based on a 6 month conflict. Nobody knows for sure how much it is going to cost.