Despite all of these problems and this laundry list of glaring systematic issues, the crowning achievement of Battle for Azeroth’s endgame is that it still remains enjoyable all due to those two pillars of raiding and dungeons. That won’t last forever. As the expansion goes on, and the grind necessary to progress becomes even more demanding and the time spent in content that simply isn’t fun increases, it will be harder and harder for raiding and Mythic+ to carry the expansion along.
They seem to have expected some things, though, see adding pets with aquatic damage (gun and ooze) aswell as a resistant cockroach to stop us from cheesing everything with elementals. Yet, a fact their damage output is low combined with shields not checking for racial damage means this mechanic prevents a lot as you mentioned. The last boss has got an ability to remove basic shields so perhaps that was not in oblivion either… unlike the reactive damage. Also, an ability that forces swap altogether with an ability which prevents from being swapped, including critters? I can't say I like it.
If there would be a transmog server #1, all transmog vendors would transfer there and the market would get destroyed fairly quick. In general, Roleplay-Servers like Argent Dawn or The Aldor are better server for selling transmog. On high pop servers you have a lot of other players selling stuff and as a result, low prices. On low pop servers prices are acceptable, but you have no buyers. So there is not recommendation for a server really. Its up to you.
Now that you have the addons and the websites needed for success, you are ready to make auction toons. You will want two auction toons, one on the same faction as your main toon and one on the opposite faction. Do not use your main toon to make the auctions that get you gold! This is one of the greatest mistakes you can make because after a while, people will get annoyed with your prices and selling quantities and begin to blacklist you from groups and some will even boycott your products. Do not risk this happening to you, but rather, create an orc for horde and human for alliance and get them outside the nearest auction houses in Orgrimmar and Stormwind respectively. (As a personal preference, I tend to avoid names with bank, mart, or sell in the name because when negotiating outside of the auction house, you seem less personal). All the addons we downloaded should be enabled for these characters as well.
From “The Burning Crusade” expansion, weapons like Klinge der Zauberei, Die Nachtklinge and recipes for different weapons are really valuable. The best example is Pläne: Teufelsstahlangschwert, worth 500.000+ Gold. These items are World Drops, you can find them in all raids and dungeons. I don’t know any Open World Drops, but that does not mean there are none. Another great transmog source are world bosses and rare spawns on Outland.