Shades

I have some questions about my exercise regime. I should first say what I'm going for, I think. I am not trying to become particularly strong or ripped. I just want to lost weight and be a little healthier. And possibly raise some self esteem.

So far, I run about 4 miles every other day. And by run, I mean mostly run with 2 very short walking breaks. I increase the distance and take shorter breaks as I can. The only kind of exercise equipment I have are a set of free weights and a flat bench. I do bench presses, biceps, triceps, forearm curls (both directions), and three shoulder exercises (straight above my head, straight to the sides like flapping, and lifting directly from arms down to arms straight forward). Finally, I do sit ups. Based on a class my brother took in college, I do the sit ups in 5 separate groups- arms behind head, behind neck, across chest, lifting legs (which also strengthens your knees, good for my recovery from knee surgery), and sitting up kind of sideways.

I have seen some slight results, so that's encouraging. However, I don't want to end up looking like a freak. Some stuff I've read on this board has scared me.
- I don't do any back exercises. What are one or two I can do? How do I do them?
- I run a pretty good amount, I think. Do I need to do leg exercises, or will my legs get any bigger?

Keeping in mind that I don't intend to become a body builder or anything, I'm just trying to lose weight and firm up some.