You are correct; NPCs are set (and listed in the data.000 file), though they can move around, or enter / leave the game world at certain points. See the following for more details.

Teleporting Anywhere, via hex editor

Reviving dead NPCs


BTW, it really isn't necessary to reload a lot to get the best possible equipment (the game gets easier as it progresses, anyway). I wasted too much time doing that my first game. Playing again I would limit the number of tries to get something good, and only do so for potentially very good equipment (dragon armour, etc) or at the very beginning of the game, to get started.