(1) From the given figures it seems that the nuclear magnetic moment of the nucleus has the same orientation to the one of the nuclear spin. This can be seen from the fact that the lowest energy (hyperfine) level is given by spin number m_I = +1. (a positive g_I factor).
And since the distance between the energy levels is always the same, it seems that the hyperfine splitting strength is independent of the nuclear spin orientation.
(2) For low temperatures, the lowest energy levels will be the first to be filled. This means that most nuclei will be orientated in the m_I = +1 direction, with possibly a few in the m_I = 0 direction.