I'm 5' 5" 120 lbs. I think the small will...
I'm 5' 5" 120 lbs. I think the small will fit me, but I'm a little concerned about the length of the jacket. Does this jacket stop below the hips, like many jackets, or above the hips?
Also, what temperature ranges will this jacket keep me warm at when I'm only wearing a t-shirt underneath?
The small will probably go below your waist but it isn't a long fit like a parka. As far as temperature, the softshell fabric is warmer than a straight hardshell, but without any layering you'll probably be comfortable standing around in weather down to ~40 degrees. If you're active, you can go much lower. I ski tour in a very similar jacket with just a tshirt underneath and I can stay toasty when it is 20 degrees outside.