What I haven't been able to find is just how much of the animal/wild instinct does feeding live retain? In other words, does NOT feeding live lessen the aggression of the snake and thus the likelyhood that it may strike the handler (me)?
I have a boa, which I feed f/t (I don't like bringing home big, live, angry rats), and it still hits the frozen rat like it would a live one. So no, it doesn't affect their overall feeding response or decrease the likelihood that it would mistakenly bite you.

Also, I've heard/read about feeding the snake (regardless of live vs prekilled) on a box or enclousure outside of its tank to avoid food association with your "hand going into the tank", is this true?
100% not true. If you argued that feeding a snake outside of tank would decrease the likelihood that they'd bite your hand inside their enclosure, you could make an equally convincing arguement that the snake would expect to be fed EVERY TIME IT WAS REMOVED. Both of those arguments are totally false, but you run the logic through and it makes no sense to say that a snake would be less likely to bite you simply by being fed outside of their enclosure.

Additionally, ball pythons can be especially shy eaters and being removed from the safety of their hide inside their own enclosure can be enough to completely shut off their feeding response when placed in the "feeding box."

A snake will be less likely to bite through efforts of the keeper, such as handwashing after handling rodents or other pets, learning their body postures to predict behavior, avoid startling the snake, reaching without looking, etc....