2021-06-18
A copy of a spell can be countered like any other spell, but it must be countered individually. Countering a spell with storm won't affect the copies.
2021-06-18
If a spell with storm has targets, you may choose new targets for any of the copies. You can make different choices for each copy.
2021-06-18
Spells cast from zones other than a player's hand and spells that were countered or otherwise failed to resolve are counted by the storm ability.
2021-06-18
The copies are put directly onto the stack. They aren't cast and won't be counted by other spells with storm cast later in the turn.
2021-06-18
The triggered ability that creates the copies can itself be countered by anything that can counter a triggered ability. If it is countered, no copies will be put onto the stack.