Yes sleeper is best for railfanning! And 16515/75 and 12080 are all 2S trains. This trip takes 2 full days from YPR. For SC, you can see connecting night trains from SC- YPR which reach before 07:00 AM. For return you can catch 12649 to kcg from YPR. Use the new kudla express 16575 to save time.