Well personally mine is about 8 watts. I use my 4xNiMH AAA's which under load put out about 4 volts (fully charged 5.4V, 4.4V under load) with a 2.2 ohm atty. Which is 8.8 watts freshly charged, Watts = Volts * Volts / Ohms. Then it kinda stabilizes at around 8 watts, I know it's time to change batteries when it drops down to about 7. Freshly charged I pull 2A (Amps = Volts / Ohms), the benefit for using a regulator is so that you have a consistent nominal voltage. I don't have much experience with regulators so I'm not sure how it would behave if you tried pulling more amps than it says it can handle. I'd assume it would fry it, but it might just reduce the output voltage. Say you attach a 1.5 ohm atty and fire it up, that would be 3.3A at 5V (which I don't recommend doing BTW, 16.7W, super hot vape lol).
Also you should use either 20 AWG or 18 AWG wire (I usually use 18 AWG). Steeljan on youtube has some great tutorials on how to wire stuff up.
This video was probably one of the most useful ones I've found. I love all her videos, she's great.