The answer to your question is the point of the experiment, so knowing the answer would defeat the point. Assuming that they are the same length, I have a feeling it would be the thick wire due to its larger cross section.
No because the thicker the wire would mean less electrical resistance therefore less heat and less light. But the exact answer will depend on if you are asking about a thicker filament inside the light bulb or about thicker wires feeding current to it? If you’re asking about a thicker filament then the answer above is correct. If thicker wires feeding current to the lamp, then the answer will depend on how much the total resistance of the full circuit (of bulb and wires) changes when you change the feed wires.