Forum:Help with spell speeds

me and my friend have been dueling and this has always been one of the biggest problem.

scenario:

okay so it is my turn. i set a mystical space typhoon and many other cards with the spell speed of 2 or 3, than i end my turn.

now its my opponents turn he plays the card heavy storm(spell speed 1).

the arguments my friends and i have made is that 1) you may not activate any of the set cards b/c they have already been destroyed, and u can't activate a destroyed card b/c spell speed only applies if you activate the card.

2) you may activate the set cards even though heavy storm was activated because they have a higher spell speed.

another scenario could be

instead of heavy storm my opponent activates xing zhen hu and my cards (which are of higher spell speeds) can not be activated or activated?