Board Thread:Theories and Speculation/@comment-890307-20161205161301/@comment-3568954-20161222143935

Itachi did not have huge chakra reserves. Itahi's databook rating for stamina is 3 which is the same level of stamina that kakashi has and kakashi stated that he has horrible stamina. if you don't know what stamina is. stamina is the blanket term for physical and spiritual energy IE chakra. anyone who has over 3 in stamina has more chakra than itachi. kisame's is 5, sasori's is 5 Deiara is 4, Kakuzu has a 4.5 in stamina Orochimaru has a 3.5. so in the end No itachi didn't have the second largest chakra reserves.

as for sarada gaining the Mangekyou sharingan. the uchiha were bound to the curse of hatred which could have been the reason that the Uchiha required hatred to gain the Mangekyou sharingan. Sasuke and Naruto ended the curse of hatred. meaning she might be able to gain the Mangekyou Sharingan witout seeing a friend die