Forum:Couple questions

got a couple of questions for you guys? 1. if i have a stardust can i use it to negate my oppenents own stardust if they use its effect to negate one of my magic or trap cards?? 2. i have zanji and granmaster and attack a stardust with zanji can my oppenent use stardusts effect to negate zanji effects to destroy it? 3. can i activate dd crows effect during the battle or damage phrase? 4. i have a royal oppression and i try to special summon grandmaster and my oppenent negates it i can just return grandmaster to my hand right?? 5. is there a limit on how long i can look at my oppenents hand for example if i trap dustshoot them? and can i only look at his monster cards only?

i guess thats it..thanks