Welcome to the boards
Loot is level based, and random. I don't think I got anything even mildly good before I hit at least lvl 10. Unique, yes but mostly quest related so far so me (and that's about 100 hours played already).
You can enchant with sigil stones, without using the enchanting altars but be careful -
first do the MQ part about the Oblivion Gate in Kvatch, then the Gates will start spawning all over the place.
As for the souls, well indeed, that's lvl based too, ie the monster you meet.
Petty:
* Deer
* Dog
* Goblin
* Mudcrab
* Rat
* Sheep
* Skeleton
* Slaughterfish
* Wolf
Lesser:
* Boar
* Ghost
* Goblin Skirmisher
* Horses (all kinds)
* Imp
* Scamp
* Skeleton Guardian
* Stunted Scamp
* Timber Wolf
* Troll
* Zombie
Common:
* Ancient Ghost
* Bear, black
* Clannfear
* Faded Wraith
* Flame Atronach
* Goblin Berserker
* Headless Zombie
* Minotaur
* Mountain Lion
* Skeleton Hero
* Spriggan
* Will-o-the-Wisp
Greater:
* Bear, brown
* Daedroth
* Dread Zombie
* Frost Atronach
* Goblin Shaman
* Land Dreugh
* Nether Lich
* Ogre
* Skeleton Champion
* Spider Daedra
* Storm Atronach
* Wraith
Grand:
* Gloom Wraith
* Goblin Warlord
* Lich
* Minotaur Lord
* Xivilai
I use mostly fire, it serves me well for almost anything. But enchanting is fun here, ie there is no more unique armor, or impossible to find, like in MW. When you hit a certain lvl, glass, daedric, etc will be everywhere. So have fun and experiment, you'll always have more.