skyscraper location/construction

what i want to know is are skyscrapers located specifically in relation to other nearby skyscrapers ? , given the close proximity do neighboring skyscrapers have effects on each other?- what about wind channels that get artificially created by lots of skyscrapers? - is this taken into account for a location? - what are the guidelines for skyscraper location?
also is a skyscraper at its most vunerable structurally to its ability to handle wind loads during its construction?