Okay, let's see if I can reply to these sensibly...
- The heat of carrying them around in the desert would affect the state of most normal weapons, and he didn't tell the boy that he was supposed to make weapons until just then. Also, it would make more sense to make the weapons there than to make them somewhere else and then have to carry them all the way there - less energy wasted, see.
-No, because he makes unique weaponry, see. Also, what I meant was that carrying them in the desert would affect how well they would work - they'd be pretty much ruined by the time the two would get to the village, but the people have enough provision to maintain weapons as long as they are still of reasonable quality.
-I didn't say it was a big oasis, or that it had been small. It's dried up a lot, so it's much smaller, but there's still water. Also, there's enough groundwater stores and throughflow to maintain it, but it'll dry up soon.
-No, it isn't. That would be unreasonable. The village would be built around the largest oasis available.
-Yes, fairly small.
-Oh, they can export and do business and stuff with other places - that's part of the reason they need ways of defending themselves, so the merchants or tradespeople can have guards.
-They're affected by monsters and things like everywhere else, just not as often. And they want to be prepared for when they might have to fight, such as in territorial wars and such or something of that nature. Why do the armies of peaceful countries still train during times of peace?
-They're not down to the last man or anything; as I say in the previous statement, they simply want to be prepared for attacks and to be able to defend their people and traders.
-You can still find raw materials in the desert. Besides, this is a fantasy setting - there will be available materials for uncommon practices in unlikely places.
-Nooooo, I said she took shape in and then came out of the darkness. Imagine a black mass appearing and then something slowly taking shape from that.
-Um, where is that? You'll have to quote that part, I can't really see it :/
-Because she's mentally unbalanced, and doesn't really think things through. She came because of a strong urge that she decided to follow on a whim. She didn't plan anything, she just sort of decided to do what she did.
-Because of its horrible appearance, and the fact that it is extremely unnatural and didn't exist there before. His whole arm is mutated, remember. He thought that she'd destroyed his arm or something, and it was the sign of a curse, like a slow, poisonous death.
-He doesn't know what it is, as aforementioned.
-Garoth? Through sheer force of will. He's very sturdy, is Garoth.
-Not very. She's mentally unbalanced, as I said before; in her current state, she doesn't think very clearly, and goes mostly by instinct, most of which are based on destruction of some sort. To put it in some sort of context, her alignment is extreme chaotic evil - she does whatever the hell she wants, which usually involves shinde, shinde, koroshi - death, death and murder.
Hope that helps somewhat. That Inuyasha thing's sort of odd, since I never really read or watched Inuyasha, so sorry about that ^_^
Made my characters all a bit older, to make it more believable, so now the protagonist is 15, the sorceress 14, the Dos Blados guy 15, the Darkling 15 and the Talaban 16.