Thinking about getting a Prius...

Welcome to Prius!
Your dealer can change the backup beep so that the car beeps only once when you put it in reverse. He can change the seatbelt beeping to be less intrusive (I keep mine obnoxious, I want passengers to buckle up). There's a door lock setting they can also change, I think it's so that all doors unlock when you put it in Park. Most dealers will do this for free at the first service if you ask.