What is a "world drop" and other questions...

[Shriek]

I haven't seen the guide you're looking for. A lot of this information just has to be gleaned from the Alla/Thott databases, in-game experiences, and the rare useful post on the official forums. This kind of information is _precisely_ why I visit the Lurker Lounge. :)

Is this correct?

Pretty much.

Can any monster drop from the world list?

Again, pretty much, with a few limitations.

Drops are limited by the level of the mob, so that you don't get a cracked sash dropping from lvl 60s, and unless you're running an instance a little early, I've found that it's extremely unusual to have an item drop that you can't yet use.

Drops are also limited by mob type. Humanoids can drop cloth of appropriate level, beasts can't. You won't find feathers on an ooze creature (though you might find some interesting stuff in there).

While almost, if not every mob can drop from the "World Drop" table (which seems to include grey, green, blue, and purple items), some have a higher chance of dropping higher quality, namely bosses, elites, and rare spawns. AoE trash, on the other hand, often have a very low chance of dropping anything (though there is rumor that some actually have a higher chance than normal for epics).

Blizzard also seems to be fond of giving individual mobs a special loot table in addition to the typical one for their class, to promote farming, such as with the dungeon set pieces. There are several profession recipes that only drop from mobs in Tyr's Hand, a somewhat obscure camp of elites.

Many of the "good" items people look for from certain bosses and such seems to be predetermined and have set stats, nothing random, but then there is random items as well, how does those work?

There are green items in every level range, on the world drop table, that roll a random suffix like "of Intellect" or "of the Monkey" as was the case with Diablo. There are a few items tied to a smaller drop table that can also spawn with a random suffix, such as the Atal'ai gloves, which only drop from six specific mobs in the Sunken Temple.

The stats generated by the suffixes are fairly tightly controlled by the item's level, but there can be a little fluctuation (e.g. a Peridot Ring of Fire Resistance might be +19 or +20). The stats on items without such a suffix are static. Every Bone Slicing Hatchet is just like every other, until you add enchants.

I can probably need some heavy upgrade on items I use, but were to look?  And what alternatives exists from for example tailoring?

Personally, I like to use Thottbot. The profession lists are pretty easy to go over, since there aren't that many in a given level range that'd be useful--just pick the "Tailoring" link, hover over the icons to find where your level range is on the list.

Finding appropriate drops is tougher. Go to the "Find Armor" search page, and narrow it down as much as you can. Think it's time to upgrade those Berylline Pads? Choose "Shoulder", "Cloth", "Drop", "Superior", and set the level (the item's level, not the required level--this takes some browsing on Thott to get used to) to 52 - 57 or so. You only get three items back; one's no good for a priest, one's bind-on-equip (which indicates that it's a world drop--check the prices on the AH, but don't plan on finding one), and the other looks pretty good--pull it's page up, and you can see that you need to go find Rotgrip in Maraudon.

Alternately, you can search by the mobs instead. You know that the Sunken Temple is a pretty good level for you, so go to the "Find NPCs" page, and select "The Temple of Atal'Hakkar" and "Phat Loot"--ignore any result with less than about 100 kills--there's a lot of trash out there :(. Pick each boss and see what they might have for you.

Preferably I like printable information.

Not a lot there--I have gotten some use, at least, out of printing the profession lists from Thott--but that's a lot more useful when you already know what the items are.