1) From the picture, you can see an equidistant splitting between the energy levels of different values of m. This could mean there is a magnetic hyperfine field that causes this splitting.
From the fact that we have m=+1,0,-1, we see that the nuclear spin is 1 (but that was shown in the left picture). I am not sure what else could be identified for the nucleus.
2) At low temperature (so low thermal energy), the nuclei will have lower energies than at high temperatures. This means that, at low temperatures, more nuclei are in lower energy states. In the picture above, that lowest energy state is m=+1. Thismeans more nuclei have their spin oriented in the positive z direction. If you “put together” all the spins of the nuclei in the ensemble, we will find an orientation with more “arrows” oriented to the upper half.