According to NEC 250.32-d a main CB is not
required in the garage panel,fed from a 50A CB in my house panel if the neutral and ground buses are separate,or does 225.32 hose me on the single
management and safe switching procedures?
225.39 (D)Rating of disconect requires that the feeder to have a minmum rating of 60 amperes. If you only had two two wire circuits you could get by with not less than 30 amperes, 225(B).