-you can probably find a bmx caliper that will clear the balloon tires, but you are likely to find the performance underwhelming
-The right hand lever can operate either brake. In the UK and many other places, the majority of bikes are set up right/front and left/rear. In the states, some folks call this set-up "moto". I think i'd prefer moto if i wasn't so accustomed to the USA standard.
-The bmx diameter for controls tends to be the same as the diameter of cruiser bars, so *most* bmx brake levers and grips work fine on *most* cruiser bars. However, the diameter of the bars where the stem clamps to the bars is different between BMX(7/8" is standard) and *most* cruisers(1" is standard.)


-rob