>Besides 'look at everything', 'think about the
>area/inhabitants holistically'. I guess I wonder just how much
>information, how many flags/attributes of mobs and areas, or
>hidden quests I don't know how to find.

It's probably not quite as bad as you think.

My wild-ass guess is that 70% of the quests in the game skew to low levels. In this case I'll define that as 1-15. Most or all such quests are found either in hometown areas or in areas intended for low level characters.

Most quests will be offered to appropriate characters if they walk into the room with the NPC that offers the quest, or there'll be some kind of automatic tip-off that something is going on. There are, of course, exceptions, but most of them will either be in explore areas or areas where you could reasonably be expected to be doing a lot of searching in order to solve a quest which would fit the aforementioned mold.

All that being said, I found a quest with the last character I started (an NPC offered it to me as I walked in the room) that I never knew existed, so it's clear to me that I don't know everything.

>I suspect that to exhaustively find all the quests a certain
>race/align/class character has available to them, I'd have to
>go walk through many areas every 5 levels or so. So then, I
>just have to play enough chars to cover each race/align/class
>to find all the possible challenging, supersecret quests
>available. But I realize I'm trying to be too exhaustive. Can
>I count on quests being offered to characters within the
>area's recommended levels? How about the 1-40, or ALL areas?

I can think of one or two exceptions, but for the most part, yes.

The narrowest quests I can think of are of the form "this class only" and there aren't too many of those. You're more likely to see a quest for only people with a certain skill, and then the reward will be a boost to your percentage in that skill.