Legal amphetamine.
Therapeutic dose of Adderall is way smaller than "recreational" doses of amphetamine. It has to be carefully calibrated by therapist. Higher doses will lead to headaches and, paradoxically, tiredness and drowsiness — not stimulation.
False. You're right in that it won't help them very much -- specifically because taking overdoses of amphetamines tends to lead to things like insomnia, tachycardia/dehydration, and mania/psychosis.