Who owns them?
Mark Cuban is the majority owner of the Mavericks. He created most of his initial fortune by co-founding broadcast.com which streamed radio broadcasts. It was bought by Yahoo for $5.9 billion in 1999. Today he is involved with a lot of investments with Todd Wagner where 2929 Entertainment and HDNet are among their more notable ventures.
The most famous minority owners of the Mavericks include Ross Perot, Jr., the former majority owner of the team, and Todd Wagner also owns a stake.
Does ownership its facilities and other teams?
Kind of. It shares ownership of the American Airlines Center with the NHL's Dallas Stars and their owner, Tom Hicks.
Cuban owns a minority interest with the United Football League as some games are aired on HDNet. He has been interested in buying other major sports teams in the past, including the MLB's Chicago Cubs and the NHL's Pittsburgh Penguins but he was ultimately unsuccessful. He is right now interested in buying the Dallas Stars. If the Cowboys go on sale, you can almost bank on Cuban expressing interest.
How do I think ownership is doing?
I think they're doing a good job selling out the arena on a regular basis, and they're a consistently good team every year with Dirk Nowitzki and the players put around him, whether it was in the Steve Nash and Dirk era; the Dirk/Josh/Devin Harris/Terry era; or the Dirk/Caron/J-Kidd/Terry era. They haven't won a title yet, but with the collection of talent here, it's not out of the question.
Cuban was recently sued by Perot for financial recklessness with the team, since the team has in recent years acquired many of their core players through trades with large contracts that put them well past the luxury tax limit, and believes the Mavs are close to being financially insolvent. Cuban claims that the team is financially secure because he is.
So even considering the financial craziness, as long as Cuban can foot the debts the Mavs incur, well, then he's doing a good job making the Mavericks the most competitive team in a town that would otherwise only care about the Dallas Cowboys, Texas Longhorns football and to a lesser extent, TAMU Aggies football.