Pretty much what everyone else said.
The harness is a cool idea because you can attach a lot of accessories to you that you might need.
Side note, be careful with hooking the scoop to you. Depending on your comfort and swimming ability in the water, you might want to use a dive belt with a quick release buckle if you are going to attach a lot of items to you. Also being that you are using a wet suit, you may have to use weights.
The wet suit should keep you close to the surface so the vest that inflates with a co2 cartridge is debateable, again depending on ones comfort and the conditions that one hunts in.
Definitely you will want to use dive boots, the one that has the zipper on the side is the easiest to use.
Do like the majority until you find what is the best way for you, drag your scoop with one hand. Depending on if you have waves, the scoop also gives you support, kind of a third leg.
The dive knife is a good idea because the monofilament in the water can cut you if you get tangled in it. Also the hooks that can be tangled up in there can really cause some pain.
The other important thing is know your ability with water.