For Itachi, I'd say +attack

While for Shisui +Nin

I use +attack -ninjustu for itachi since he's pure tai(mostly) and +ninjustu -attack for shisui since you kinda don't want to lower his defensive ability plus his mixed attack so besides his chase lower attack doesnt change much

Same here. +att -nin on my Itachi Anbu and +nin -att on my Shisui.

if you're running LM, i would recommend for shisui to use +Nin, - Res since Root buffs res by 100% while maintaining your damage

true but even then shisui still doesn't like being punched or he dies.

+nin -res and ability scroll round 2 resistance.

If you are stacking Shisui then he's not going to die :P besides everyone will aim to kill aAnbu itachi first

he dies, he dies. He is made of paper tissue.

id - base life since his life is already so low, can be compensated by treasured tools

i would - defense for shisui as his res growth is on the higher end