Can anyone point me to a few good sites to learn about mods, plug-ins, etc, for Morrowind? How do they work? What are the problems with them, if any? How do you manage them? Get rid of them? Do they make the game too easy? ... and other stuff like that.

While no newbie to CRPGs, the only "mod" I've ever applied to any CRPG is a patch !!

When you start the game, and the start-up menu appears, click "data files". Here you can turn on any mod you have installed. You can turn them off in the same way, but your existing savegames may not function properly.
You can play one game with some mods, and another game with other mods, it is that easy to switch them.

Only problems that I can think of are mutual incompatibility, eg. if two mods create something in the very same spot - that will crash the game. Such problems are usually mentioned in the readme.

Installation is very simple: you have only to put modname.esm file in your Data Files directory, and sometimes other files in their respective folders.

The game is too easy or too hard as it is, depending how you play it. Mods bring some freshness and make the game interesting again.

There are many sites with mods, for example:
http://thelys.free.fr/mods.htm
http://morrowindfiles.com
just do a google search for "morrowind mods"

http://www.gamebanshee.com/morrowind/locations.php

This is a pretty good site, but www.morrowindfiles.com is where i usually get my plug ins, although lately the site is down very often.

Some mods can make the game easier, but others make it tougher to beat your opponents, like the one where you down download new kinds of monsters, and even flying firebreathing dragons.

Some mods can cause the game to crash, others can come into conflict with eachother somehow, so i'd suggest you take one at a time, and not a whole bunch, otherwise you'll be spending more time figuring out what's wrong, than you'll be playing Morrowind.

Helpful info, thanks !!

Are there any mods that have a quasi-"official" status, i.e. tried true and tested, and used by many?

I think on Morrowindfiles.com all mods are rated, and you can see how many times it's been downloaded, so that gives you an indication of how popular it is. You should also try Bethesda's official site, for some more useful info about it.

ever since morrowindfiles.com was hacked I am very afraid of going there. you don't know what the hackers left behind.

I prefer going to this one instead.

http://www.rpgplanet.com/morrowind/

There are mods that have fully official status, <a href=http://www.elderscrolls.com/index.php?url=/downloads/media_wallpapers.htm&bg=05>made by Bethesda</a>.

hacked? when did this happen......Although i never go to the site, who would want to hack morrowindfiles?

People who have nothing to do but harrass other net users. Usually they do that for fun, not even money.

That's no good....i wonder how it can be stopped