I'm type 1 (seemingly with insulin resistance) and taking metformin. My ratio was 1:1-1:3, and my endo wanted me eating a minimum of 120 carbs a day, so my total daily insulin was over 200 units at one point on MDI. This, possibly in combination with other endocrine issues, made me gain over 50lbs in 2-3 months... on an average of 1600calories!
I started metformin at the same time I got a pump, started on symlin, and lowered my carbs to 60-90g per day, so I'm not sure what metformin did on it's own. I can tell you that the combination of all these things drastically changed my insulin needs and control for the better. My ratio is down to 1:5, and my total daily insulin is down to 50-65units.
I take metformin 1000 2x's a day. I was taking it with breakfast and dinner, but I found if I took it at breakfast and right before bed, my morning numbers are much better. I have issues with my waking numbers.
I had hair loss prior to taking metformin, but it doesn't seem worse since I've been on it. My weight has been crazy and random, but I think most people will lose fat when they get to lower their insulin dosages, assuming they exercise the same and eat the same or less calories and carbs.