Compatibility of heat lamps and bulbs
1 and 2, Lower is always OK, higher is not, unless the FIXTURE it is going into is rated for the higher wattage. it's the fixture that matters, they are rated for wattage based on the heat involved and the way the fixture can deal with that heat. EFFICACY of a lower wattage lamp is another issue, based on what you are trying to accomplish with it. &quot;Wasting&quot; energy is a function of the task vs the output of the device. Any energy above what you need becomes waste, but determining what you actually NEED is a scinece in and of itself.

Probably not. Again, FIXTURES are rated for a maximum wattage, based on incandescent lamps because those are typical. So if a fixture is rated for 100W maximum, it will not really matter if it is a 100W lamp or heat lamp, unless the heat lamp PROJECTS the heat to a sensitive area, like a lamp shade. Fixutre are also going to be based on the base of the lamp being up or down, so if a fixture is designed for base down, like on a table lamp, you probably cannot use that fixture for a heat lamp over food where the base of the bulb will be pointing up.

Ceramic heat fixtures give off radiant heat, heat lamps usually are for infra-red heat. Infrared penetrates deeper into soft tissue, like skin or food, but has less of an effect in heating the air around it. Radiant heat is basically exactly the opposite; heating the AIR, but not penetrating into soft tissue as much.