There are three things which determine how good the loot is:
- Zone level multi determined when you first discover the zone
- Container multi (chests will generally have better items, and chests in places deemed "more difficult" will have even better items)
- Your difficulty level (effects all random scaling having to do with player level)
first one is wrong. enemies still scale up and items too even if visit a zone early. there are a few exceptions to this rule e.g. bleak falls barrow. but most dungeons stick to this rule. the loot inside the chest and the dungeon are set in place the moment you enter the CELL. not discover them. thats wrong.
example : a chest on a dragon word wall. if you fast travel three the chest will be random. if you SAVE when you have already arrvied at the word wall the chests loot is SET. but if you SAVE BEFORE you fast travel to this location the chest will be random EVERY time you reload and travel again. this system is the same [censored] as the chest system of oblivion was.
second one is correct (your best chances are the dragon word walls on the map. thier chests have the highest chances respawn every 10 ingame days).
third one is definitly wrong chances are unaffected by difficulty level. difficulty only effects enemy hitpoints and enemy damage not loot.
the chances of finding a FULL deadric armor without smithing or conjuration ritual are very very small. without exessive reloading abuse you will have discoverd ALL dungeons and still lack a full set. same goes for dragon armors. you can however get deadric easy either with smithing (requires 5 perks) or conjuration (requires no perks but 90 conjuration and ebony items) tough the boots are bugged and cannot be looted during the conjuration ritual.
dragon armor can only be gotten effectily by using smithing. getting a full unentchanted set (so you can entchant yourself) is nearly impossible or would simply require ENDLESS reloading abuse.