Stardust Dragon tributes itself as a cost for its own effect. So if Evolzar Dolkka chains its negation effect to this, Stardust Dragon can't do anything. Not only is it not there on the field for it to be tributed again, but Evolzar Dolkka isn't destroying a card on the field.
The end result will be - Dolkka's effect will resolve, negating Stardust Dragon's negation effect. Since it's already in the graveyard, Stardust Dragon won't count as being destroyed, but that doesn't affect anything. The effect Stardust Dragon chained to will resolve as normal. Because Stardust Dragon's effect was negated, it will not resummon itself.
Yes. The Quick Effect of Evolzar Dolkka can be used twice in one turn, the only thing that matters is it has to have enough XYZ material.
Yes, that particular Quick Effect can be activated in the Damage Step.
Yes. Chain link 1 is a regular monster activation. Chain link 2, Evolzar Dolkka detaches a material to try to negate chain link 1. Chain link 3, Shooting Quasar Dragon activates its quick effect to negate chain link 2. Chain link 4, Evolzar Dolkka detaches another material to negate chain link 3. End result, Chain link 4 resolves. Chain link 3 is negated, Shooting Quasar Dragon is destroyed. Chain link 3 was negated. Chain link 2 resolves. Chain link 1 is negated, the original monster is destroyed. Chain link 1 was negated.
Is so expensive is because is an secret rare and it will be more expensive in the future!
Yes. You are still in the response window for responding to the attack declaration. Cards that respond to attack declarations are valid at any link.