Well, yes, obviously. I'd hope that leaders would think this important in all dance forms, but yes, it's definitely more important in AT.
In ballroom it's safe to assume the the follower will always be on the natural opposite foot (parallel system). Because in AT you have cross system, it's possible that a secret weight change wasn't as secret as you had hoped, or a non-secret weight change wasn't as clear as you intended. In these situations the AT leader needs to be aware of what happened and proceed accordingly. Also it's possible in AT that the follower was doing some embellishments of her own, where you'd again also want to be aware of where her weight is.
I don't mean individual movements. In the ballroom swing dances (all standard dances excluding ballroom tango), every single step comes with a lot of momentum. They are meant to travel rapidly across a large area. In AT while some movements can have momentum (particularly it seems with vals), the dance as a whole doesn't move with the same forcefulness that ballroom does, at least in a social context.Not really - it depends on the movements.
That has to do with the fact that it's a different dance.There are many other differences (posture, for example).
There are many differences in posture and other things even within ballroom. Quickstep, waltz and ballroom tango all require a different posture, and technique (also foxtrot, which has the most demanding technique. Waltz and Viennese waltz have similar posture and technique). On top of that there's also ballroom latin (which I don't dance) which has another five dances (the rumba and cha-cha I think have similar posture and technique, but the others are very different).
So, like I said I don't think a ballroom dancer will have much trouble adapting to the various technical differences they'll encounter in AT. Point (1) will be their main stumbling block simply because conceptually (not merely technically) it's different. My Point (2) is also a a conceptual difference for intl. standard dancers (but probably not for latin dancers) but it's not really a stumbling block - more of an opportunity.