Ok, so, I'm a noob, and I like tanking very much. But I always ran into problems, so I have a few questions regarding tanking gear.
Baron Rivendare and some UBRS dragon fights seemed incredibly hard to me sometimes. My question is, is it a good idea to use lowerish level 'Thorium Armors' there? (Because obviously I don't have access to Tier1 fire resistance gear or BWL resistance gear), so my only accessible option would be:
(Thorium Helm, Thorium Belt, Thorium Bracers, Thorium Boots)

I could stack these with 'Medalion of Grand Marshal Moris', 'Stockade Pauldrons', 'Skullflame Shield'. And eventually with the shadow resistant engineering trinket, the Ultra-flash Shadow Reflector (though it seems a huge effort to get it).
The important part of my question is, that this way, I would have 350-360 defense (with the 10 defense from the talent points), instead of the "normal" tanking (I'm a warrior, sorry, I forgot to say that) pre-raid gear, which would give about 390. BUT I would have 58 shadow resistance.
So, let's say that, I'm a noob, I don't care about raids, I just want to have fun at Stratholme and Scholo, would this setup be better? And would this work for UBRS, too? (58 fire resistance, 38 arcane resistance)
Another question: night elf or dwarf warrior for tanking? (not that familiar with horde, I only heard about Taurens from there). Where is the dwarf poison resistance good, at Zul Gurub? How important is that there?
3.: Why is that 2% block shield enchant so good? If a boss hits me for 1000 damage, and the shield has a block value of 40, that means that I will still get 960 damage. It seems incredibly weak to me (considering how expensive is that enchant). And this enchant increases that chance by just 2%?
4.: Stupid idea, but the Naglering:

inflicts 3 arcane damage in melee attacks.
If I would use a mage ring in the others slot, I don't know what's it's name, let's say 'Songstone of Ironforge' from blackrock depths, which increases damage and healing done by magical spells and effects by up to 18, that would mean that I would cause 21 arcane damage to every melee attacker? Would this be useful for easier 5 man instances, like let's say BRD?
5. Another strange idea, if I drop the blacksmithing, and I get engineering (anyway it would be needed for the trinkets), and I would make Dense Dynamites, would they help for the adds at the Baron fight? Is it a good idea to waste time with that? (Dynamite description: Inflicts 340 to 461 Fire damage in a 5 yard radius. (cooldown 1 min))
I mean, okay, strange idea, but those adds from Baron seems incredibly annoying, I can't keep them on me, they are immediately attacking the healer, they are the worst thing I ever saw.
6. (Sorry, I have lots of questions.) One time, at Scholomance I had -90 shadow resistance, and seemingly I got no diseases or curse or similar on me. Is that a debuff linked to a certain area of the instance? Would that cancel out completely my whole resistance gear theory?
7. At Stratholme (doesn't matter if living or undead), the first few pulls seems very hard. I don't know if it's bugged, but even if I stun the mob, it still tries to run away and chainpulls the next group, and after that the following group. Would it be a good idea to spec a bit in fury and get the [Piercing Howl] ability? ("Causes all enemies near the warrior to be dazed, reducing movement speed by 50% for 6 sec.")
Would it waste too "much resources" from the protection talent point tree?
Because for example, the "Last Stand" ability seems rather easy to sacrifice to me. I never know when to use it, 30% extra health, sounds good, but I don't know when to pop it. I can't watch constantly my health bar for this, and how will I know if the healer is out of mana? Maybe he is just casting for a second a heal spell for a mage who got in trouble or something, I don't know.
8. Again, at Baron, those "Bile Spewers", fat mobs, before Ramstein, when they started to cast instant poison, Venom Spit or I don't know what, that was eating my health away so fast, it was scary. A bad pull, pulling two of those, and I don't think that any healer could keep me alive there. Would it worth putting in the effort to farm (the gold) and to buy from some higher level players the [Ironvine Breastplate] (726 armor, +30 nature resistance, Equip: +7 defense) and [Ironvine Gloves] (454 armor, +20 nature resistance, Equip: +10 defense)? (I don't like the belt that much, and I would need that slot for the Thorium Belt).
How much nature damage is reduced by let's say 50 nature resistance? (I know that there are guides on the web, but they are so confusing, some of them includes newer patches, some of them don't, I can't figure them out.) And when a 'resist' occurs, is it completely resisted? Or just by a given percent? I mean does it cause crazy damage spikes sometimes?
So, would this solve the problem? Because this setup would give me 88 nature resistance with a night elf, or 78 with a dwarf. [So are night elvs better? (because I saw a lot of cases, where nature resistance could come handy, if I'm right even those whelps before Rend Blackhand from UBRS are casting thunder damage or what)].
9. Icy chill enchant on weapon. It chills the target, slowing it's attack speed by 25%. It seems very very nice, but it's almost always resisted at boss fights. Why? Is that suppossed to be like that? Was that mechanics modified on this particular server? Also I saw some people with 3% hit enchant on the ranged weapon (bow or crossbow or gun or something). Will that affect melee attack? Or what enchant is good for the weapons, let's say the melee weapon (if the icy chill is not that good)?
10. Also, thunder clap seems good to me, it's not resisted, and it slows down their attack speed by 10% (it's just a bit of pain to change the stance to battle stance). Is it any point to use the demorilizing shout?
11. Also what easily accessible weapon is good? I know what shield I want, the Skullflame Shield, because that gives 10 shadow resistance (it seems even better than the Draconian Deflector in this regard), but what weapon? Would it be good to use 'Hand of Edward the Odd' for tanking? (45 damage per second. Very strange stats, +13 intellect, and 'next spell cast instantly' buff.) But it would be relative easy to get from AH...
12. And just one last question about enchants, the +4 all stats chest enchant seemed somewhat popular to me (but more for rogues). What does "all stats" mean? Just agility and stamina and strength, etc., but no resistances? I saw some kind of "Greater Resistance", +5 all resistances enchant for chest, too, would that be better for tanking? Or in general what enchants should a tank use? I saw a +20 fire resistance head or legs enchant, too, but it comes from a quest, with a "Lesser Arcanum of Resilience", I can't make that, it would be an immense work. But (in theory) would that be better than for example paying for a 1% dodge AQ20 cloak enchant?
Well, that's for now.

I will come back with other questions in the future.

Also, I would like to mention that I found a nice tanking trinket for noobs (like me)

1% dodge, not very much, but it comes from a level 45-50ish quest from Stranglethorn Vale. It's a quest, it's easier to do it, than to farm General Angerforge at BRD hoping for a Force of Will trinket drop.
Also, an interesting idea from me. The "Super-Seller 680" vendor from Desolace (in the southern area) sells unlimited amount of Scroll of Protection III (180 armor for 30 min.) and Scroll of Agility II (9 agility for 30 min.) for 4 silver each. They seem a good option to me.

In summary, please help me, give me ideas, give me tips, tutorials, anything, because World of Warcraft is one of the most complicated games I ever saw in my life. Especially considering tanking, huge amount of mistakes can be made.
And even if I dream about raiding one day, and getting best in socket, full, pre-raid gear, it seems impossible to get there if 5 mans are that much of suffering sometimes.
This game is a pain!!