A:
No seconding is required for any nomination, although members often do so to indicate their support of a candidate.
(RONR pp. 423-424.)
Technically, unless the bylaws require them, you don't even need nominations when you vote by ballot, because members may vote for any qualified person, nominated or not.
But nominations are valuable because they tend to significantly reduce the time and effort that would be needed otherwise.
(RONR p. 422.)
Also note that in small boards secondings are never required for any motion.
(RONR p. 478.)