An owner selling their own real estate is exempt from real estate licensing in most states, and that exemption is about brokerage. It says you don't need a license to negotiate the sale of property you own. It doesn't speak to whether the state regulates the act of dividing and marketing lots, which is a separate body of law and where the subdivider registration you found comes from. Some states require a subdivider or land developer filing, a public report given to buyers before they sign, or a specific disclosure package once you're offering a certain number of lots created from one tract. The threshold and the paperwork vary a great deal by state, and a few states have almost nothing. This is one to confirm with a real estate attorney licensed where the land sits before you market lot one.
At a much larger scale there's a federal disclosure regime for subdivided land sold across state lines, and the exemptions are numerous enough that a six lot project is a different world from a 100 lot one. Same advice, ask counsel rather than guessing from a forum.
On insurance, the product is usually a vacant land liability policy. It covers claims from people getting hurt on ground you own, which on unimproved land means trespassers, hunters, dirt bikes, and an old well or foundation nobody told you about. Premiums on small rural parcels are often a few hundred dollars a year. It doesn't cover the plat being wrong, that risk lives with title insurance and the surveyor's own professional coverage. Ask the surveyor for a certificate showing they carry errors and omissions before you hire them, since their seal on the plat is what everyone downstream relies on.
