Amaroth

First of all, you need to know that there are 2 types of items - texture ones, and model ones. Texture items are only textures applied on character model, they can bear some information about how should character model change when they are equipped (for example gloves, boots), but in fact, they are only textures. So there is no actual way of opening such items in Blender, but what you can do is opening character model there and placing textures of such items on it. Having said that, there is the second kind of items - model ones. Headpieces, shoulderpads, weapons, shields (hand-held stuff in general) and in some cases belts on MoP+ have all models, and yes, in that case, you can open them in Blender. In case you want to edit textures, you need to get their BLP files - thats usually done by using WoW Model Viewer (WMV). There is BLP plugin for Photoshop, and there is also PNGtoBLP (and vice versa) converter, so you can also turn them to PNGs, edit them in that format and then convert them back. In case you want to edit models, there are two ways. You can convert models to m2i and open them in Blender m2i plugin (I've personaly never done this), edit them there and then convert them from m2i back, or you can export them from WMV as OBJ (or different standart 3D format), edit them in Blender and then go through standart OBJtoM2 conversion process, which may be way more tedious than m2i way afaik. If you have no idea what am I talking about, use Google :P. And check beginner tutorials, here, on Modcraft, on my YT channel, whenever, to get some decent idea about how things in game client work and how to do such things.

No idea, I am not very experienced with more advanced spell stuff.

I highly, HIGHLY doubt that in order to become friendly to Horde/Alliance you need to be friendly towards some "Horde" or "Alliance" faction. Those two are not an actual "factions". They are whole group of factions (for the lack of better term). Factions you have used are probably supposed to be used just for cathegorization in Reputation tab or something like that. I don't think you can become friendly toward whole "faction" of players and all their NPCs, at least not by using this method. Both Alliance and Horde are actually just FactionGroups. They contain dozens (if not hundreds) of player and NPC factions, which are an actual factions this spell targets. By creating whole bunch of spells making all NPC factions in FactionGroup you would probably make player be friendly towards that faction, although I am not sure wheter that would work with player factions themselves to prevent for example PvP. Btw, I have no idea what could cause your crash. I just want to point out that your idea as whole probably can't work, not this way.

Normals are part of model. 3d stuff, absolutely nothing to do with game engine (apart from fact that it uses them, but so it does with UV maps, topology, vertex paint and so on).

Noggit? No, it is not. But you can swap invisible/broken model with some existing and visible model to make that thing display in Noggit and then just delete it. Done.

Stop confusing people with fixing this in hex guys. Most of those who cannot figure out what Skarn wrote on their own are intimidated by 010 and this is just way easier. And for them, even quicker. I myself have never used 010 for fixing this crap.

I have encountred similiar sort of behavior on my server which is running on dedicated VPS-hosted server with Debian distribution. Sadly, I wasn't able to find real solution, friend of mine did, so I am unsure what was really going on. AFAIK security of OS was blocking connections sent from authserver to worldserver of some IP addresses (yes, this as problem only for some IPs), identifying them probably as malicious activity. Thats all I can tell you about this matter, sadly, but it can help you with finding correct direction what to look for. Check your antivirus/antimalware software, firewall (on both server mashine and router), those kinds of stuff. Maybe problem isn't with your IP/ports (yes, ports, PAT/NAT can be annoying things to deal with), but with your actual security solutions on your network.

Thats exactly a reason why one should read whole manual :P.

Welcome and good luck both with learning stuff and making something cool looking happen :P.

.mdx is just an extension, there are no actual .mdx files (or they are very, very rare). Idk why are .mdx extension to be used instead of .m2 ones (probably some historical reasons), buts its a common practice in all WotLK DBCs and when not followod, stuff may not work. Thats pretty much it. Green always means texture could not be loaded (which usually means it could not be located). Nothing more, nothing less. All textures used by a model have paths to them written directly in its m2 file. Just open it in any text (prefferably 010) editor and search for .blp paths. You will find all paths to all used texture there. The same applies to WMOs as well.

To get any original ADT, simply open all MPQs in Data folder by using Merged Mode option in MPQEditor, then browse world/maps/ directory. To find out which ADTs you need... just go to those locations in Noggit and take a look at ADT tile coordinates. No magic here (and at the same time, no other way here, as long as you don't want to calculate coordinates from server coordinates, which is something I can't advise you to do).

But... I have explained all here already. All of these are WORLD DATABASE tables bro :D. Its MySQL thing. No tools. No DBCs. Just MySQL database tables.

Uh... what tool for guards do you exactly need? I have just absolutely no clue wth are you talking about, what tool, what for, what is here for what you'd need any kind of specialized tool whatsoever? Oo

There is no real difference. Both works. But imagine you'd be building something like Stormwind out of multiple objects. Not very convenient way, its easier to build such city with a lot of connections between parts/buildings in 3D. On the other hand, making just one huge object won't make it very easy for you to re-use any building used in that city. So it has some drawbacks as well. Yet again, its up to you, and depends on what you would like to achieve.

For WMO plugin, Skarn has linked it already. You may try to download the newest test beta version, if you wish to, too. Repo is linked in that topic. What should geometry look like I discuss on my YT channel, as well as plugin installation. Guards... I have never tryed to do this, even while I wanted to multiple times, but it seems fairly simple. world.points_of_interest defies coordinates for "flags". They are called from gossip_menu_option (called from gossip_menu, which is called from creature_template). The last paragraph of your question... I don't get it. Just make a WMO and spawn it to your map? Where's a problem with that? Or make a new map, with that WMO on it. Or make a new map, which is only made out of that WMO. All is possible. It depends on what you want to achieve.

Well, if there are any custom files you wouldn't find in any blizzlike client version, you are screwed and need original listfile.