Honestly it looks like three pieces. There is a waist cincher, or under bust corset, a piece to cover your midriff, and then a bra. If you want this not to chaff you might consider either stitching some kind of lining on the piece or wearing something under it. I make a lot of leather underbust corsets and waist cinchers. Everyone who wears them always puts them over something.
If you look around you can find a bikini pattern by macalls or whomever and use that for the top. The patters are made to be sewn true, but you can use the pattern to get the shape you want. Generally when making a bra pattern like that you want to make a triangle, and when you wet form it to your dress form you will get the rounded shape to it. Wet forming is not hard, just takes practice and a bit of elbow grease. If your dress dummy is similar in shape you to, remember that leather shrinks when you get it wet and let it dry. Its not a lot, but when dealing with items that cover unmentionables you want to make sure that nothing is too small. I know you are prolly going to want to go for accuracy but remember this, there is the five foot rule when costuming and it can save you a lot of head ache. If it were me, Id stitch a bra to the leather bra cups so that you dont have to worry about chafing, and remake the rest of the bra in the green leather.
Now if you are going to do the underbust corset piece as one piece, that is going to be a bit harder than it sounds. You are essentially making a huge waist belt. I typically make my cinchers in three pieces, just for ease of making them, and for comfort, but when is costuming comfortable? But if I was you and you were going to make the belt as one piece, Id lay out the pattern on leather, cut out the whole thing. Then get the pattern that you want to wet form into it, and press it. Though I think you could tool the leather to get the pattern, it would be faster than trying to wet form it. Also I think you ought to go with a lighter leather, maybe 3-4 oz leather, no more than 5. If you go heavier I think you are actually going to 1) make this harder on yourself, 2) lost some of the accuracy with the piece, 3) run into issues with attaching things. 4) make the piece heaver than it needs to.
The issues with heavy leather is you are limited in what you are going to be able to attach pieces together with. Other than tubular rivets, and copper post rivets, there are no long shanked rivets I know of. anything above a 6oz leather really makes it hard to attach things. Her armor honestly looks more like a fashion accessory than real armor. A lot of my friends in SCA who make their own armor use copper post rivets, and they use really heavy leather. Id go with a lighter leather to save yourself logistical issues with things after you get it cut out. You can tool lighter leathers, wet form it, or whatever. Just when it comes to ease of making the item it would be simpler to use no more than 5-6 oz leather. Thats typically what I use. I made the mistake of trying to use heavier leather for a cincher, I had to get longer grommets in order to finish the piece. The pattern in the piece makes it easier to hide the stitching, and you can use embroidery thread instead of sinew to sew with.
The hood seems pretty easy, just have to get some sueded leather, us e the bigger hole punch and get some of the leather cord that tandy sells and use that to sew it, check out your costume patterns for hooded cloaks and stuff. A basic hood is nothing more than a square with two sides sewn together, and then attached to the collar of a cloak.
Leather might be a natural material, but it does hold heat. Its going to be really hot this year, yes you are going to be wearing very little, but that waist piece and everything else is going to bake you pretty good.
Im sorry Im a bit all over the place, but Im just thinking as I go here.
If I was you, Id get cut out three separate pieces, the underbust corset, the part that covers the midriff, then the bra. I would then do your dying, and decide if you are going to tool, stamp, or whatever with the pattern on the piece, IF you are going to stamp or tool, then you are going to have to wet form and tool at the same time, or else you will lose the pattern cause the leather will get wet. You have to bind the leather to the dress dummy once you get to the point of wet forming it to fit your shape.
Here are a few examples of my work:
cincher 1
cincher 2
if you need any help drop me a line
either here or on gmail: halafax@gmail.com