Most houses in my neighborhood have chimneys with three flues. Some have the
flue heights staggered, while some are all the same. Does the staggering
help prevent smoke exiting one flue from going down another? If so, how
different do the heights have to be to be effective? Does the order matter
(SML or SLM)?

Also, how much space does there have to be from the highest flue to a
chimney cap?

Thanks.