Sean Payton said today that Saints won't be back in New Orleans for at least a month and that for the time being the team will practice in the Dallas/Ft. Worth area. For this week, they're using AT&T Stadium as a practice facility. Going forward, they may use that facility or the football facilities at TCU and SMU as practice facilities. Saints owner Gayle Benson chartered two planes to Dallas over the weekend with players and their families and is currently picking up the tab for hotels and meals.
As far as where they'll play their Week 1 home opener vs. the Packers, that's still up in the air. AT&T Stadium is out as an option, even though the Cowboys will be on the road, as there is a concert scheduled there for the Wednesday after the game and the contract requires that set up for the concert begin a few days beforehand. The NFL wants the game to be held in an NFL stadium (I'd assume due to need for communication with New York) which means the Alamodome is out as an option (plus UTSA has a game there the night before so it'd be a tough turnaround to get the venue ready for an NFL game the next day). Among the possible venues that could be available for a game that Sunday include Jacksonville, Miami, Seattle, Denver, San Francisco, and Arizona.