It isnt a necesity, but it will definately help a lot. It will make the gun a lot more consistant. Before you get a reg, make sure your co2 is anti-siphoned tho. Tha tjust means there is a tube inside that makes it so that no liquid co2 can get into the reg or gun.
Well, thats what regs are for, some just work well w/ co2. Its Nitro, nitros is what you put in cars bro...Spyders can handle nitro, or compressed air, or n2, or HPA so you wouldn't need a new gun lol!