Even though the schedule hasn't been released to the public I would imagine that it is already pretty much set so the arenas know what dates they have open.
Probably, but my hunch is that their are only a handful of buildings that will have multiple U2 nights that could even potentially cause issues for the NBA. Plus, doesn't the NBA work on / announce schedules later in the year - you'd think they'd try to build matchups at least in part on previous year's results (i.e. Miama and LA on Christmad Day this year?)
Plus, now that the NHL is in the toilet, seems like the buildings would want to book the revenues.