Yes, you dont need C3,IC1,C2 when it should only protect 
L1 blocks HF noise (should be 2A cappable).
the 1N makes in case somebody messed up the polarity a safety, and in case the input drops it prevents the C1 from getting discharged.
D2, can also be a 20V type, this limits the voltage.
C1 (Ultra Low ESR) smoothens out small ripple.
C3 could be removed, but im used to always put C3 and C2 with a 7805 