While exploring a dungeon, I found a letter from Princess Morgiah(Is it related to the main quest)? I reloaded from before I entered the dungeon, and noticed it was still in my inventory in a different dungeon, on this separate save. Is this a bug? I don't remember obtaining this letter on this save data and I'm not a fan of bugs helping me in any way, so I'm going to reload again if it is. Also, why is that letter in a dungeon?

I believe a post-zombie brought that to you.

Such as when I recieved a letter from Lady Briesanna? I found this letter in a loot pile in a dungeon, but did not and never was notified of it being delivered to me in another save file, yet I had it in that save file. If the letter was to be delivered to me anyway, then ignoring it for about one ingame week would cover the amount of time that it would have taken for it to be delivered, right?

You get letters in very weird ways, I would not be surprised if someone left it there for you.

Do you remember that dungeon I couldn't get out of and how I reloaded my game because I couldn't get out? I found the letter in that dungeon, but when I reloaded, the letter was still on my character, even though I reloaded from before I went into the dungeon. So now, my problem is that I don't want any bugs helping me, but I don't want to reload and lose more loot from another dungeon I entered, so I want to be able to continue playing, but justify this letter coming into my possesion, somehow. I'm not quite sure how to do that, though. On this character, I did not find the letter in a dungeon and I did not receive it from a messenger, so I believe it is in my inventory due to failure to clear save data from another file when I reloaded.

Assuming this is the first letter from Morgiah inviting you to come see her in Wayrest.
No, it's not a bug.
Yes, it's part of the main quest.
Usually it just shows up in your inventory. (I really suspect you already had it when you entered that dungeon but just hadn't noticed it).
I think that the quest/letter showing up is either a function of time or, more likely, triggered by you making it to a certain level.

(Just some advice: Put off going to see her until you get some more experience).

(Other than talking to Lady B, there is nothing you HAVE to do as far as the main quest goes. I usually wait 2 to 3 months before starting the MQ just gaining rank in guilds and gathering equipment).

That's what I'm doing, and I have to say, despite the randomly-generated quests, cities, and dungeons, I'm enjoying exploring. I've joined a knightly order(although now I'm wishing I joined a knightly order in Wayrest) in Daggerfall and Daggerfall City has become my base of operations. Just so I don't waste a thread, are there any Dark Elves in this game besides me(Barenziah, Morgiah?)? I also found a holy tome that's worth 2500 gold. What are all these religious items(holy tome,holy water, religious items, etc.) I keep finding? Are they useful for anything, or should I just sell them? Also, I don't have enough magicka to cast levitate or teleport, so are there any items that would do that for me? I need both of these spells, or at least teleport, but I can't and never will be able to cast them with my current character.

Dark Elves: I don't know. I've really paid no attention to the ethnicity of any of the NPCs except Barenziah. ("The Real Barenziah" is a 6 or 7 vol. biography; interesting).
Religious items: Useless, sell them.
Magic items. Best/only? way I know of to get those magic items is to get access to an Item Maker (i.e. a person who can enchant items). You have to be either level 5 in the Mages Guild OR level 5 in the Temple of Julianos to gain that access.

(IMHO the 2cnd most important thing I do in Daggerfall is making lvl 5 in the Mages Guild). (The most important? Making lvl 8 in the Mages guild, gaining access to its teleportation system).

Thanks. Also, are skill trainers supposed to be able to train me up to 51%? I thought they could only train characters up to 50% in anything, but a skill trainer was able to increase one of my skills to 51%.

Karethys, Morgiah, and all in Wayrest are all Dark Elves. Or some sort of "mix" between them: you can see because of the way their eyes are.

EDIT - Not even Barenziah, which appears in Morrowind, looks like a Dark Elf. I think this was a design decision or the like.

Yea, somehow the art design on the NPCs and the PCs got a little mismatched. Basically, if you meet any NPCs with red eyes, they're supposed to be dark elves.

There are ones that cast levitate (mistakenly named by the game as "___ of venom spitting", which gives me a really odd mental image of how exactly you're levitating yourself). I don't think any random magical items are ever enchanted to cast Recall, though.

I think Andyfall fixes the the art for the Dark Elf npcs.