Six Samurai, Dust Tornado, and Mystical Space Typhoon

I was recently in a duel with a member of LDA and we began to argue on if "Grandmaster of The Six Samurai" was actually considered a Six Samurai or not. I tried using the effect of "The Six Samurai-Zanji" with "Grandmaster of The Six Samurai". I thought I was able to do this because many people I have dueled with before allowed me to and also the fact that he tried using Dust Tornado and Mystical Space Typhoon to negate the activation of my spell and trap cards but from what I have been told from other people this does not work.
One situation that occured:
I tried to negate the effect of one of my opponents spell/trap cards with "Dark Bribe" then the member said that he could negate the effect with "Mystical Space Typhoon" which he had set on the field at the time. I am not sure if this is possible or not but I would like to be told what the actual card rules are so I do not mess up anymore.
-Zaithain

1- "Gradmaster of the Six Samurai" is considered a Six Samurai since he has Six Samurai in it's card name. Any effect of any other Six Samurai are applied when he is on the field. That means that Zanji get's his effect.

2- In no way MST and DT can negate a card's eff that has already been activated. Rules are that the effect of a card that has been activated is always applied unless another card immediately and specifically negates it. It doesn't matter if the card is destroyed or is in the graveyard. The effect of Dark Bribe goes through.

~Yami Yugi~

yes grandmaster is a six samurai and you cant chain tornado dust or MST to a counter trap card like dark bribe cuz it is spell speed 3

Thank you,
I had thought the member was wrong.