One other thing is that launchers and other boxes that control weapons are DAL-A equivalent, so you have to be rigorous about your requirements and testing to ensure that a missile never accidentally fires. This drives up development costs as well, since you have to do a lot more work to verify and validate the system.

It depends what you mean by "SV salaries" but defense contractor developers can make a lot of money, especially compared to other software jobs in the NOVA/Maryland area (which are not paid nearly as well as SV).

They produced approx 40,000 between '59 and '94, so around 1,000 a year. So I would assume they broke even.