Two separate documents, two separate jobs. The note is the borrower's promise to pay. The security instrument, a mortgage or a deed of trust depending on the state, is what attaches that promise to the real estate and gives you a remedy if the promise breaks. Without the second one you're an unsecured creditor holding an IOU.
Getting the house back means foreclosing, and the process is set by state law. Some states use nonjudicial trustee sales, which can run a few months. Others require a court case, which takes considerably longer and costs more in legal fees. A contract for deed, also called a land contract, is sometimes pitched as a faster remedy because you keep the deed until the buyer pays in full, but several states treat a substantially performed land contract like a mortgage and require you to foreclose anyway. Which category your state falls in is a question for a local real estate attorney before you choose the instrument.
On taxes and insurance, the mechanism you want in writing is either an escrow arrangement where the servicer collects and pays them monthly, or a monitoring service that tells you the moment a payment is missed or a policy lapses. Unpaid property taxes can create a lien that sits ahead of yours, and an uninsured loss can destroy the collateral your whole position rests on. You should also be named on the buyer's hazard policy as mortgagee or loss payee so the insurer notifies you and the claim check isn't handed over without you.
During a default you'll often be the one advancing those taxes to protect your lien position. Budget for that rather than being surprised by it.