(My impression is that reliably defining, much less comparing, brain regions is very tricky--though necessary).
B. Traditionally, beginning with Broca himself, these areas were identified on autopsy and retrospectivey correlated with deficits. Recently online, non-invasive imaging processes, e.g. fMRI, can monitor blood flow (BOLD) to regions. Newer methods on on the way with greater accuracy and especially response time.
TMS (Transcranial_magnetic_stimulation ) offers a way to create the effects of a lesion in a small brain region by temporarily disrupting neuron activity by a rapidly varying electromagnetic field. One recent study claims to localize "morality."
A. Severed in "split-brain" surgery; see videos on Vicki, Joe.