I've been working on my own Praetor Suit for about a month, all with EVA. I decided to not use templates, because every time I try to I end up changing it a ton anyway. All hot glue too, so this thing is definitely not done correctly. I find that hot glue fits my creation process pretty well though, as I constantly tweak stuff to my liking and you can't really do that with cement. I'm definitely not going to wear it in hot weather anyway, so I don't really have to worry about anything melting.
Regarding the leatherish stuff under the armor, my plan is to do all the solid looking padding in foam and wear a cheap leather jacket under it in order to fill in the bits that have to flex. It looks pretty good as far as I can tell, but I'll get a better idea once I paint the chest. The thing I've really had to make sure of is that the armor really sits far off of your body. In all the pictures of the OG suit, you can see that his shoulders are actually a little above where the green chestplate starts. Everything above that is just padding, leading right into the neckpad. My chestplate comes about 2-3 inches away from my chest, and the shoulders are about 3 inches wider than a doorframe. With the shoulder pads being so massive, I've found I can just add in foam underneath the actual plating and let the larger segments glide over it. Foam is really versatile depending on how you paint it, so I'm going to make it all look like worn leather with some acrylics. The downside of making the suit as bulky as it is in the game is definitely mobility though, but it's worth it.
Some tips I have:
-You can see that between the shoulders and chestplate I put some reinforcing horizontal pieces. These help to keep the shoulderpads in place. On the game model only the piece on the left is there, but I took creative liberties and put in a pretty well hidden one on the other side (and the same on the back.) The pieces aren't glued in place on both sides, but rather are glued onto the chest and connected to the shoulders with an elastic strap, to allow the shoulders to move in and out slightly. The shoulders are glued onto the chestpiece at the top, as I couldn't find a way to have the shoulders rest on my own arms and still look correct to the game.
-I see that you have an Eternal helmet, but if you decide to make your own I would use an EVA template off of etsy instead of 3D printing. The sanding required to make a print of that size look good makes me want to jump off a roof, and the helmet is a lot more durable when made out of foam. For the visor I bent up a piece of acrylic with a heatgun and fitted it in with a dremel (I goofed and cracked the acrylic on the right side when I tried to bend it and it was too cold. I'm too lazy to replace the whole visor so I just put a big gash in the side and passed it off as battle damage.) To get the glowing effect I lightly sanded where the acrylic meets the helmet and glued EL wire onto the inside of the acrylic. It looks fantastic in the dark but is pretty dim in daylight. EL wire is really cool, if you can I'd incorporate it wherever you can. I also put it into the red hole in the chestpiece.
-You should absolutely get a dremel if you can, it makes cleaning stuff up really easy. The variable speed ones are nice. It leaves little fuzzy bits sometimes but you can kiss it with a lighter and they'll dissolve.
-I put buckles in to attach the arms. It works well to keep them in place, but it's hard to connect them by yourself. They are glued onto the top of the bicep piece on the outer edge, and there is a strap hanging down from the shoulder that the other half of the buckle is attached to. The arm and forearm are both permanently attached with a nylon strap at the elbow.
As you can see, I'm nowhere near done yet so a lot of the other things I'm experimenting with might be changed. If you like, I can update you in the future. Hopefully it'll expedite your building process, although I went and did a lot of things I really didn't have to so it's been taking me a while.