The salary numbers are from a Fox Sports article (Olgun Uluc) published in October 2018,which was talking about the 'Next Stars' program.
Here's the relevant quote:
"The average NBL salary is now $AUD152,000, a league spokesperson told foxsports.com.au; with an average of $AUD122,000 for local players. "
I allowed for 11 players per roster to get the average team salary.
For the various percentages and rules around the cap relationships, I relied on the NBL announcement of salary cap changes for the 2016/17 season, back in March 2016. Here are the relevant bits:
"- Rosters increased to 11 contracted players.
- Salary cap in future years determined by averaging all teams' salary
- Aggregate salaries of at least 5 players on each team must not exceed $400,000 in 2016/17.
- Salary Floor implemented - Clubs must spend at least 90% of the Salary Cap."
According to a post on this forum, earlier this season, the $400,000 has been continued as 40% of the salary floor in subsequent seasons to 2016/17.
It's possible that further changes affect some of those rule changes in 2016 but I've heard nothing to that effect. Unfortunately, I don't know how to get a hold of the current NBL rules around salary cap arrangements, to confirm the above are still correct.