If steal wool was the major heating elemet would it ignite peices of it? Also what color would it burn? I would like to use this for photography

It depends on the thickness of steel wool and the amount of available oxygen. Magnesium ignites at approximately 473°F, while burning steel wool can easily reach 1000°F when fed oxygen. Keep in mind that it will be easier to to to ignite the magnesium when the particles are smaller but still allow gaps for air. Also keep in mind that when you are photographing the magnesium will burn extremely bright and can cause eye damage, so i would be sure to use welding rated eye protection. Also magnesium burns at an impressive 5610°F, so be sure to stay far back and place it in a container that won't melt or explode (metals melt and glass explodes). Lastly magnesium fires are class D, which means you ABSOLUTELY NEED a DRY POWDER fire extinguisher on hand during these experiments. CO2 extinguishers actually feed magnesium fires, and others do nothing. Never attempt to put out a magnesium fire with anything but a dry powder extinguisher, and of course never attempt an experiment if you have any doubts about it's safety. Hope this helps!

dose it work as a firework fuse?

This magnesium ribbon has many scientific and recreational uses. Magnesium burns at very high tempatures and is incredibly useful as an ignition source for anything that requires such temperature to ignite (thermites for example). As a fuse for normal fireworks, yes it would work, but it has a chance of going out, burning too quick or too slow, and setting other things on fire. I would always prefer visco fuse or cannon fuse for ignition of normal pyrotechnic mixtures, its incredibly safe, reliable, and cheap. Hope this helps!

What is the shelf life of this ribbon does this have an expiration date?

It will oxidize over time from exposure to air, which could make it more difficult to light. but the oxidized layer can be removed by pulling the ribbon thru fine sand paper, steel wool, or even common sand in a survival situation. The drier and less exposed to air it is the better it will keep.

Its magnesium...its used for many different things..one that comes to mind is flares as it burns ext brute..it also produces its own oxygen as it burns giving it the ability to burn under water. The military uses it in aerial flares and as a part of incendiary devices..