Additionally in terms of slowing down
Again, a heavier aircraft needs more track miles.
Not necessarily. If your VNAV allows for the weight and places you higher if you are lighter, you won't notice any appreciable difference in slowdown-distance.
Certainly though, from the same point in the sky, say 5000ft at 20nm at 250KIAS, a heavier aircraft will take longer to slow down than a lighter one for the reason I showed above: the longer/larger weight vector contributes more to the effective thrust, meaning that either the heavier will glide further or, if forced onto the same flightpath eg 5000ft/20nm to 3000/10nm, it won't slow down as much.