Both should be positive values, so that should be the difference, not sum.
I'm with you so far (though you meant stores, not taps).
Initial acceleration is 9.8 m/s/s. That is what I meant, and failed to sufficiently clarify, in my last response. My apologies.
Not over periods of time, no. The feather has a much lower terminal velocity. But in the instant that they are dropped, yes, they do.
Drag/air resistance will actually have a greater effect as his body has a greater surface area-to-mass* ratio than normal. That's what causes him to reach terminal velocity sooner, and therefore have a slower terminal velocity.
* - Even if storing weight doesn't store mass on some level, it at the very least duplicates the effects of having less mass to a reasonable degree.