Yes, before re-rolls, unless a special rule specifies differently.

This section introduces such things as mighty wizards, magical spells and sorcerous items into the Warhammer game. In the Warhammer world, magic is a very real force - a force to be both feared and respected. Only beings that possess awesome mental and physical power can even hope to bend the powers of magic to their will. Lesser persons would be consumed in an instant their minds torn apart by unfettered energies and their souls dragged to the darkest underworld by cackling daemons. Even the most accomplished of sorcerers walk a narrow path at the edge of sanity, between ultimate power and eternal damnation. In the Warhammer world, all magic is derived from the same source - the fickle Winds of Magic. From the Realm of Chaos in the north, this magical gale spills across the world bringing with it the power for great good or evil. The potency of the Winds of Magic vary from time to time, waxing and waning as the rent in reality in the north expands and contracts. Wizards must therefore learn to use best what power they can, tapping into the winds to channel its energies into their spells, or disrupting its flow to dispel the incantations of others, Thus, magic is not a sure strategy for any general, for though it can sweep aside whole armies when it is strong, it can just as easily slip through the grip of a caster with no effect.

Magic

This is normally specified in the item's description, but if there is any doubt the following applies: The unused dice that can be stored at the end of the magic phase are those of the wizard himself and those of the pool. In the following magic phase, all stored dice go back into the pool.

Of course. The only exception to normal dispelling is that power dice are used as dispel dice.

Yes, bound spells can be cast this way, as can Tomb King Incantantations, and so on.

'All spells in play' covers all spell, including those that are not technically 'Remains in play', but have effects lasting a certain amount of turns.

Warhammer Fantasy: 7th Edition

Magic - Frequently Asked Questions
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Do the rules for double 1s and 6s for dispelling spells follow the same guidelines as the one for casting spells (ie. do the double 1s and 6s have to be considered before any re-rolls, unless otherwise specified)?
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Some magic items allow the player to store excess dice in the magic phase. Are these dice common or do they belong to the wizard carrying the item?
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Another Miscast table, #5-6 result query. Can the opponent use a Bound Spell or ability which works like a Bound Spell (e.g. Prayer of Sigmar) if this result is generated?
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Miscast table, #8-9. Are the 'remains in play' spells the only ones to be dispelled, or does it also cover 'spell lasting one or more turns' which cannot be usually dispelled?
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Magic - Frequently Asked QuestionsURL Copied!

Do the rules for double 1s and 6s for dispelling spells follow the same guidelines as the one for casting spells (ie. do the double 1s and 6s have to be considered before any re-rolls, unless otherwise specified)?URL Copied!

Some magic items allow the player to store excess dice in the magic phase. Are these dice common or do they belong to the wizard carrying the item?URL Copied!

Another Miscast table, #5-6 result query. Can the opponent use a Bound Spell or ability which works like a Bound Spell (e.g. Prayer of Sigmar) if this result is generated?URL Copied!

Miscast table, #8-9. Are the 'remains in play' spells the only ones to be dispelled, or does it also cover 'spell lasting one or more turns' which cannot be usually dispelled?URL Copied!

Magic - Frequently Asked Questions
URL Copied!

Do the rules for double 1s and 6s for dispelling spells follow the same guidelines as the one for casting spells (ie. do the double 1s and 6s have to be considered before any re-rolls, unless otherwise specified)?
URL Copied!

Some magic items allow the player to store excess dice in the magic phase. Are these dice common or do they belong to the wizard carrying the item?
URL Copied!

Another Miscast table, #5-6 result query. Can the opponent use a Bound Spell or ability which works like a Bound Spell (e.g. Prayer of Sigmar) if this result is generated?
URL Copied!

Miscast table, #8-9. Are the 'remains in play' spells the only ones to be dispelled, or does it also cover 'spell lasting one or more turns' which cannot be usually dispelled?
URL Copied!