In the 2009 season: the Colts and the Saints. First time in NFL history two teams have been 12-0 in the same season.
Kansas City Chiefs are currently the only undefeated team as of week 4 at 3-0
The Miami Dolphins. The New England Patriots went undefeated until the superbowl.
This is true. When the Patriots and colts squared off in week 9 of the 2007 season, it was the latest meeting of undefeated teams in the history of the NFL.
Every team has one bye week during the season.
All NFL teams play sixteen games in a seventeen game regular season. Each team gets one "bye week," a free week off.
Miami Dolphins it was a shorter season though, only 16 weeks. 1 bye week so 15-0
Alabama, Texas Tech, Ball State, Utah, and Boise State as of week 12 Alabama, Texas Tech, Ball State, Utah, and Boise State as of week 12
16 weeks, including conference championships. Most teams will be finished by week 15. Teams typically play 12 regular season games, plus a conference championship game if applicable, and if chosen a bowl game.
Your question is unclear. At the start of the season everyone is winless. In the second week lots of teams are winless.
Week #3 vs the Eagles, week #8 vs the Giants, week #10 vs the Colts and week#16 vs the Titans.