Does the prayer become void if the Imam says during the prayer: (And whoever exchanges faith for disbelief has certainly strayed from the straight path), while the correct verse is: (And whoever exchanges disbelief for faith has certainly strayed from the straight path)?

Such a linguistic error does not invalidate the prayer unless the person commits it intentionally. Most often, this error occurs due to forgetfulness or a slip of the tongue. In this case, the prayer is valid. Al-Bahuti stated in Kashshaf Al-Qina' that a linguistic error that does not alter the meaning does not invalidate the prayer. However, if it alters the meaning, then intentionally committing it invalidates the prayer, but committing it due to forgetfulness does not invalidate it and is excused. The imamate of its perpetrator is not prevented if it was due to ignorance, forgetfulness, or an affliction.