Magic the Gathering: Since all creatures go to the graveyard at the same time...?

tokens disappear as soon as they touch graveyard, exile or your hand, they only exist on the field, it's like a state based effect, think it is one actually, you don't get priority to it, same as how if your life reaches zero you can't play a spell to gain life to counteract that, however when emrakul is put into the graveyard, it's ability is put on the stack which you can respond to so you could suffer the past when emrakul is put in the graveyard, however the owner would still shuffle their library seeing as how nothing was done about it's ability on the stack

No you can't. Token does go to the graveyard, but they instantly disappear before you get any priorities to cast a spell.

you can play suffer the past in respond to emrakul's shuffling ability to remove any cards before they get shuffled but not tokens.

Going to the graveyard cannot be responded to unless there is an ability on the stack.

Any time a creature has zero longevity or less, it is sent to the graveyard as a state-situated effect. It is not sacrificed (so it doesn't set off results like Mortician Beetle), and it is not destroyed (so Indestructible and Regenerate can't guard against it). It isn't important if the intent of it having zero longevity is transitority ot not. Additionally, Ghul Draz assassin and identical results do not put counters on the target creature, they directly adjust the base stats of the creature. This is colossal in the case of a creature with +1/+1 counters on it that survives the result.