First of all, if you're going to be a sailor now, you'll have to learn that it is called "line", not "rope".
More: A Piece of Rope ...
Parts & Accessories
This is a cable-lock I made. It is just 3/16" coated steel cable from the hardware store, with crimp ferrules, and a big steel ring in one end. The ferrules fit through the scupper holes on the boat, but the steel ring does not. Together with any padlock, this will secure the boat (or several) to your truck, roof rack, a tree, or anything else that is handy. You can take this cable with you, it will give you peace of mind if you leave the boat unattended to go exploring on land.
The object is not to stop a determined thief - you can't do that. It is to stop someone from casually taking your boat with their bare hands. Don't lock the boat by the handles - they are easily cut with a pocket knife and cheap to replace. Run the cable through a scupper hole, and a thief would have to destroy the boat to steal it.
The marks from crimping the ferrules in a vise are evident, but you can just as easily just hammer them. Length is as long as you need it to be, I guess mine is about 10 feet. 3/16" cable is flexible enough to make the small loops needed. As you can see from the rust, I've used this rig for years. I stored the combination of the lock on my phone, in case I forget it.
If your boat doesn't have scupper holes, you can probably find someplace to thread the cable though, or make a suitable hole in the seat.
Real side handles make necessary tie-down points for transport, and are well worth the cost of adding them if your boat doesn't have them. This is a good model that uses two screws at each end to secure it. Even better, if you can reach inside the hull, use bolts and washers instead of screws. Kayak plastic is pretty thick though, and the screws have not been a problem.
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This is for sit-on-top kayaks with closed hulls. Open-hull sit-inside kayaks don't really need hatches.
You can order any kind and size of hatch on eBay. They are easy to install - just trace the hole on the hull and cut it out with a jigsaw. A hatch like this one has a storage bag for small items like keys and phone, which removes for access to the inside of the hull.
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Your new boat probably came with a paddle. I've never seen a boat come with a good paddle. It is just a starter, to get you going. Get a good paddle that is the right size for you. It will make a world of difference. Keep the old one for a spare. Rule of thumb: your paddle should be about your height. If you install a thick seat cushion, you might want to go a little longer even.
I regard my paddle as an emergency signalling device as well, which is why I like the yellow color pictured, especially if your boat is some camouflage shade of green.
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Don't spend a fortune on a PFD, or Personal Flotation Device, commonly known as a life preserver. Unless you plan to go far offshore in deep water, you will never need it or wear it. Most of the places I go, self-rescue would be a matter of standing up, or a couple of strokes to shallow water or the shore.
More: PFD & Other Required Gear ...
This is a scupper cart. It is a set of wheels that fits in the scupper holes of the kayak and lets one person wheel it around like a wagon. The big advantage of this sort of cart is that when you get to the water, you can pull it out, flip it over, and stick it in the top of the kayak. Then off you go - no need to double back to put the cart away. Also, you'll have it if you get somewhere that you might want to portage.
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To transport your kayak, you'll need some way of securing it, whether on a roof rack, truck bed, or trailer. I recommend the type of tie-down strap shown above, with hooks on the ends, and cam buckles, not ratchets. Ratchets are a pain in the ass, and you don't need all that much force anyway. In fact, you don't want too much force, your boat is only made of plastic!
More: Tie-Downs ...