Yeah, +1. A 1watt resistor is more than enough. A 1/4 watt, or even a 1/8 watt is plenty. With a 2-battery series mod, the maximum voltage possible is 8.4V, and if you smack that across a 15K resistor, it will only make .0047 watts. The purpose of the resistor is to prevent the gate pin from "floating," so it doesn't turn the MOSFET on by accident. So, you put that resistor between the gate pin and the negative rail (positive rail for a P-chan) to carry a trickle current to bring the gate to 0 or "off" volts in case of leakage or static charge or something. It doesn't carry any part of the circuit load.
The thing about MOSFETs is they're not only switches; they can also be used as amplifiers, so a large current will follow, or replicate, a tiny one. This is because a MOSFET doesn't have to turn "all the way" on. They can be thought of as an electrically controlled variable resistor, sort of. For an N-chan resistance in the Source-Drain path varies indirectly with gate voltage. Hit the gate with small voltage, it turns on part way; increase the gate voltage and it opens up more. That 3034 is moderately sensitive; if memory serves, gate threshold is like 1V. So, just a tiny bit of charge will open up S-D at least a little, and you'll get anything from a battery drain to an autofire, depending on gate charge. The pulldown resistor prevents this by tying gate to 0V.
