No, of course not - most witches work within groups to coordinate efforts both in crafting a spell and casting the spell, a lot more energy can be gained by a well balanced group than a solitary witch. However you may not want onlookers around to put you off.
No, copying a spell is not considered casting it.
No, copying a spell does not count as casting it.
Transfiguration is spell casting.
Yes, replicating a spell counts as casting it.
No, cycling does not count as casting a spell in the game.
No, mutating a creature does not count as casting a creature spell.
No, copying a spell is not considered casting it in Magic: The Gathering.
Mana empties from your pool immediately after you finish casting a spell.
No, copying a spell in Magic: The Gathering does not count as casting it.
No, playing a land is not considered casting a spell in the game of Magic: The Gathering.
Tom blamed the unsuccessful marble spell on the lack of focus and concentration while casting the spell. He realized that he was distracted and not fully in tune with his magic, thus leading to the spell failing.
No, casting a creature spell does not allow you to draw a card.