A Q&A from ESPN. Mostly about the playoff format but some information on what is known about the bubble.
edited to remove link - looks like someone beat me as I was posting.
edited again to put it back, it was a different article.
https://www.espn.com/nba/story/_/id/29267080/what-know-know-nba-return-play
Why will people be able to come and go from the bubble?
The league is expected to house everyone at one hotel and limit access to those outside the bubble. There will be some ability to move around and eat at outdoor restaurants and have some recreation, such as playing golf. But overall the NBA is expected to keep the bubble tight to prevent the introduction of the coronavirus.
But the league and players' union felt strongly that family members be permitted to join the players. No one wanted the players to be separated from loved ones for potentially such a long duration. There have been discussions about allowing family members to enter the bubble as the season progresses. If that happens, they would be subject to quarantine before entering and tested routinely once inside.
There is the possibility of varying levels of access for some who could travel in and out of the ESPN Wide World of Sports Complex, but the league would restrict direct access to those inside the bubble.
Players who might have to leave the bubble for medical tests (MRIs, etc.) or for personal reasons might be able to return depending on the league's final protocol guidelines.