The Secretary may determine the number of individuals to be enrolled for training and reserve purposes in such service, to fix the rates of pay and allowances of such individuals without regard to the provisions of chapter
51 and subchapter
III of chapter
53 of title
5 (relating to classification and General Schedule pay rates), to prescribe the course of study and the periods of training in such service, and to prescribe the uniform of such service and the rules governing the wearing and furnishing of such uniform.