I used to brew my own mead. A lot of things can change how long it takes... temperature, yeast strain, water quality/attributes, and yes even the honey itself. While it's true that honey is "just sugar", different honeys have different pH values, and the pH can greatly affect the speed. And processed honey may take a different amount of time than raw unfiltered honey. There are also other chemical (or natural) additives you can add to feed and/or kickstart the yeast.

Oh, and how much mead you're making... at 15 lbs I'm guessing you're making a 5 gallon batch... so yeah, I've had a 5 gallon take anywhere from a couple months to well over a year to finish up. You just have to be patient.

Meads are just honey wines, as been said above. At renn faires (and other places, really), you do have to pay attention. Some "meads" are actually white wines with honey added for flavour. These are properly called pyments. Some others are actually made from honey, possibly with other flavourings. A fruit flavoured mead is called a melomel. A mead with spices (generally "sweet" spices like cinnamon or vanilla) is a metheglin. And like NewEnglander said, a beer mead is a braggot. Of course, you'll rarely see mead labeled commercially as anything other than "mead"... I think only home brewers know the other terms ;)

As for sweetness... well, mead runs the gambit. Some meads are really (REALLY) dry... others can be really (REALLY) sweet. And anywhere in between. Sweet meads are called "sack" meads. I don't think dry meads have a special term, but I could be wrong.