Citadel rarely commissions anyone in December but routinely has about 12-15 Army commissions in August due to those still needing to complete summer camp
Members of the National Guard qualify for both the federal and state GI Bill along with other enhancements such as the scholarship you mention. In some states NG members attending a state college pay no tuition, in South Carolina the College Assistance Program pays $5500 per year.
total yearly OOS cost at Yale is 90K and Harvard 82K, of course with endowments into the tens of billions they can afford to give very generous financial aid to most students needing it.