I always put at least 3 borders of different widths on my quilts. It helps to pull out the colors used in the patterm and is an easy way to make the quilt bigger. I have seen even more borders used and it looked really nice. I would use the green 2", white 2 or 3 " and the color you have pinned on as a very wide outside border. Even wider for the first 2 inner borders would be ok. If you want to make the quilt longer then make the end borders wider and the side borders narrower. I have done that and it looked nice, too. Maybe even use the floral as one of the borders. Your #3 looks great.
As a binding I think I would get the borders on first then decide on the color of it. Then go for whatever looked best of those 3 or 4 borders or even the floral, or whatever I had enough of left over. I think any of the colors you used would look good for the binding.
By the way, your quilt and colors together is very pretty.. I love that pattern and am going to make it, too.