Infret-checklist

I solved attempted 2-4 so far. Feel free to extend

List of questions I'm not sure about:
2:
3: g, h, i, l.
4: i, n.

List of un-answered questions:
2:
3:
4: a, c, o.
5: l
6: h
7:
8:
9: all
10: all
11: all