i take it that they are top cross levers. if so.....

as long as your handlebar diameter is the same, your levers should fit.
you shouldn't need new cables, since you're not changing the height of anything.
as far as riding with bullhorns in traffic, just gotta be careful about not hooking anything. i get paranoid about getting too close to girls and their purses, or getting tugged underneath a semi that may be trying to navigate streets.

but other than that, swap away.