1. I call that a multicopter. There are specialized names for multicopters: if it has 4 props, "quadcopter". 6 props: "hexacopter". Octocopter, etc. Some names give an indication on the configuration. Say you have something that looks like a quadcopter (so a square with one prop on each vertex), but each prop is doubled (so there are 8 in total: 2 "squares" on top of each other). Then I call that a "coax octocopter".

Same for VTOL (vertical takeoff and landing) vehicles. I usually use VTOL to mean "a fixed wing" (i.e. something that looks like a plane) that takes off and lands vertically, but there are different configurations. A "tiltrotor" will have the rotors facing up when taking off, and then the rotors will tilt to face forward during flight. A "tailsitter" will have fixed rotors, but the vehicle will takeoff like a rocket (so "sitting on its tail", I guess), and then transition to forward flight.