No fewer than three verses of the Torah are read for each person called. Only one verse of Torah may be read at a time to the interpreter but one may read him three verses from the Prophets. If the verses are from separate sections, then one may only read him one verse at a time. Sections may be skipped in the Prophets but not in the Torah. The amount one may skip is the time it takes to roll the scroll before the interpreter finishes (so as not to burden the congregation by having them sit and wait).
Whoever reads the haftarah leads the recitation of Shema and the repetition of Shemoneh Esrei. If he is a kohein, he duchens. If he is a minor, his father or teacher can lead the service in his place.