Kpole, congratulations on your project! It's really nice. I think you'll be much happier with a zipper. That is hoodie style, and it will stay nice and closed that way. If you're not sure about attaching it, do you know someone who can sew who can advise you?
P.S. I have a sweater-coat with toggles and while they are pretty, they don't keep the edges closed very well. Mine has snaps underneath, but even with those, the toggle loops don't stay pulled and kind of hang down. Not very good for windy weather. And because of the toggles I have to be extra careful with laundering. I once wanted to avoid the extra care and took one of my son's coats with toggles to the dry cleaner's, who ended up melting the beautiful claw-shaped buttons!
A word about zippers. There are different qualities and prices. You get what you pay for. I avoid the plastic large tooth zippers for outerwear garments because the plastic breaks and the zipper needs replacing before the garment wears out. You want a good quallity, heavier duty zipper that won't stay in a stiff, straight line but will be flexible enough to bend with the yarn as you move.







