A: About 1% of viewers, who watch it later the same day. Effectively no one watches it after broadcast day.
My guess is that the age group that watches the broadcast evening news [according to CBS Katie Couric's median age viewer is almost 60] doesn't timeshift much of anything.
Note: The data on broadcast news timeshifting I can get from Nielsen is sparse and inconsistent. The most recent set of data I can get is for the week beginning Jul 30, but it had obvious errors. This is the next most recent set of data I could get.