I honestly dont know how youd use a bulb with a tub lol? maybe have the lamp on but suspend it above the tub enough so it doesnt melt it...
An oil filled heater is just like this miny heater/radiator thingy. YOuve probably seen them before:
http://www.amazon.com/Delonghi-TRD07.../dp/B000A33B1C
I have no idea if thats a good one or good brand or whatever but thats what they look like^