[@Pathfinder]
Hey! A fellow Alaskan! Happy to have you join me, and thanks for the point with regards to the super mutants. My thinking behind them is that they (somehow, however unlikely it may be but [i]somehow[/i]) made it up from the lower 48, and are incredibly similar to the Mariposa mutants, both in looks and level of intelligence. Some differences might show up in their appearance if they, for example, hunt and use the furs as warmer clothes instead of just using leather like their southern brethren.
Do you have any suggestions on how to change them to fit more seamlessly into the lore? 
I will admit I haven't thought out the Ghouls or Super Mutants very clearly, my main focus was really on the factions and setting up the general backstory, so any help with that would be appreciated.