The first 2?'s i'm not sure.
When i eat more dark green salads i feel better and (think) i lose more.
-Don't worry about the salt, just don't eat too much.
-Vitamins only help with overall health (which possibly helps with weightloss.)
-It depends on how much, & type, of exercise you already do. I KNOW that since getting seriously with HIIT cardio 5-6 days a week a couple months ago my fatloss has seriously kicked into high gear.

You haven't been dieting for very long at all. Contrary to what you might see as slow, you've lost about 15 pounds in a month. I think that is REALLY alot and you have nothing to worry about. Weight doesn't come off in a predictable pattern of set loss. It took me a year of hardcore junk eating to get from the 120's to above 170 (which isn't very long, but hey....) so now when i think i'm losing slow i have to remind myself that it's not gonna happen in the blink of an eye. But a YEAR does go by in the blink of an eye, and i'm sure i'll be a whole lot thinner and happier by the end of the year. So try to see yourself in the long term. And when you feel like (what I describe the frustration as) a "disgusting lump" do some exercise. That's my best advice.