No team has ever been 16-0 in playoffs.
In 2009, the Denver Broncos started 6-0 and did not make the playoffs.
The 2003 Minnesota Vikings.
No, the season is long. The best teams lose about a third of the time. Even the worst team can beat the best team sometime during the season.
No. A team that outright wins their division always qualifies for post season play.
2002 New York Jets