"An infusion is the normal way we think of when we make a cup of loose tea or tea bag. We get the water hot, stick the tea bag or ball in there to steep for about three minutes, and drink the tea. We do this with medicinal herb tea if the herbs are grasses or leaves. A coffee maker uses this principle for a large amount of beverage.

A decoction, on the other hand, needs to be "cooked." You bring water to boil, throw in the herbs, and let them simmer for 15 minutes before drinking. The reason for this is that the decoction has denser material in it like roots, seeds, nut shells and the like which take longer to, as you say, draw the properties out."

YES

"Am I right in saying that the reason you need to make the teas in a steel (or glass) pot is so you don't get aluminum or non-stick coating leaching into the tea?"

YES - glass is best but most of us make do with steel...

"When I get a package of herbs, and I don't know whether to infuse or decoct, I look at the ingredients for words like "root," right? Or is it best to ask a friendly herbalist or the company I get the herbs from?"

YEP!

FYI, you can find the info for a BFC fomentation at herbsfirst.com:

Soak the combined teas in distilled water (at the rate of one ounce of combined herbs to a pint of distilled water), then soaking four to six hours, simmer thirty minutes, strain and then simmer the liquid down to 1/2 its volume and add 1/4 vegetable glycerine (if desired). Example: One gallon of tea simmered (not boiled) down to two quarts and add one pint of glycerine. Soak flannel, cotton, or any white material other than synthetics--never use synthetics. Wrap the fomentation (soaked cloth) around the malfunctioning area and cover with plastic to keep it from drying out. Leave on all night six nights a week, week after week, until relief appears.

BOB