A) Thats i not gunner, thats driver and every tank has this. check your tank also , manual vision facility is available when camera is not functioning.
B) The huge smoothbore cannon fired HEAT rounds that could kill any T-72 with a single shot.
moreover , Armed with a 120 mm rifled gun, the Arjun is believed to be capable of firing APFSDS (Kinetic Energy) rounds, HE, HEAT, High Explosive Squash Head (HESH) rounds at the rate of 6-8 rounds per minute and the Israeli developed semi-active laser guided LAHAT missile.
But India didnt choose because Rounds are expensive and india dont have luxury. for PAK these ammunitions are enough.
We dont need to through mountain to kill a cockroach when it can get killed by slippers.