My personal preference is for solo canoes over kayaks, but I know a lot of hunters love their kayaks. Agree with the advice to practice self-rescue. I would suggest wool clothes - including base layers - backed up with dry clothes in a drybag. You can wear rain gear over your clothes, especially bibs. I'd advise rain bibs over chest waders as if chest waders flood, you're (literally) sunk; whereas bibs can drain water out the cuffs. Obviously wear a PFD. There are (more expensive) specialty PFDs that accommodate kayak seats and the double-paddle stroke; conventional PFDs of course work but if it's uncomfortable you're likely to take it off in frustration. On that note, unless you are hunting ducks, get a high-visibility PFD and rain gear. If motorcyclists are advised to "dress for the crash, not the ride", then cold-weather boaters should dress to be rescued. Have multiple ways to start a fire, in your pack and on your person. It's tough to flick a Bic when your hands are numb and shivering, let alone build an efficient fire-lay. You might vac-pack some tinder and kindling and keep it handy in case you wind up needing to warm up in a hurry. I've seen ice fishermen use road flares to light emergency fires.
Pack everything in dry bags. Either label them or color-code them. I found some glow-in-the-dark duct tape at Menards and use a Sharpie on that to make labels. You can also use reflective tape the same way. I'd rather have an orange boat and a camo net to hide it with, than a camo boat, if I need someone to come rescue me.
I'm not sure how cold March gets in OK, but I would guess it's not too different that October in MN. Not to be a buzzkill, I would advise against trying to teach yourself safe boating in the cold. Safely set yourself up for success, get proficient in your kayak during fishing season, and hit it hard in the fall.