I don't agree that the system is successful in the NFL because of the natural stoppages. I think the system is successful because coaches and officials both know a contentious decision can be questioned/over-ruled.
In the NFL, calls are a lot more black and white than they are in the NBA. The most commonly challenged calls in football (whether the ball-carrier stepped out of bounds, fumbles, catches) can usually be decided one way or the other by looking at the replay.
In the NBA, there are only really three calls that are always clear-cut right or wrong: out of bounds, last second shots, and three-pointers. Everything else usually depends on the judgment of the official making the call (charges/blocks, fouls, etc.) So if you're going to institute replay for three pointers, that can be done on the fly without stopping play by a 4th official. It seems silly to stop play for an out of bounds call in a game with 70 or 80 possessions for each team. And we already have replay for last second shots, so if you want to stop play to review shot-clock violations, be my guest. But I don't think it would help the NBA enough to justify the additional stoppages in a game that many feel is already becoming more boring every season.
As far as annoying delays go, that argument just doesn't hold water. If you have a LIMITED number of challenges available to each team and, as with the NFL, teams are charged a time out if their challenge isn't upheld, then you haven't really stopped the game any more than usual. In fact, you probably wouldn't notice much time differential at all if the types of plays being contested included whether or not there was actually a personal foul committed. (If there wasn't, the guy wouldn't shoot the free throws and play would resume, for example).
Like I said, I think that foul calls are far too subjective the majority of the time to be subject to review. And then that brings in the issue of fouls that aren't called. As a matter of fact, refs would probably be slightly more hesitant to call fouls at times if they felt the call would be overly scrutinized.
And honestly, I don't think the system you described (of course, that description isn't comprehensive) would make much of a difference. I doubt that very many calls would get overturned, especially foul calls, since you would need absolute proof to reverse a call. As such, coaches probably wouldn't challenge very many calls to begin with.
It's not a matter of allowing free challenging. I firmly believe this system could work in the NBA. Again, we're talking something like maybe two challenges per game. And, if it's gonna cost a team a time out, they're certainly not going to waste those challenges.
Probably not. I just don't think it would be effective enough to make a difference in the quality of the officiating in the NBA. It's a lot different from the NFL in that most calls in the NBA are subjective to a large degree, so it's much harder to make an irrefutable case against them. There are, on occasion, terrible calls that a 3rd grader could point out, but in a game with so many possessions, they tend not to have a detrimental effect on the quality of the game being played.
If you're going to review 24 second violations and three-pointers, in addition to already looking at last-second shots (which the NBA approved because it requires no additional stoppage in play; it's done at the end of quarters and overtimes), then those reviews should be automatically done by a 4th "review" official on the sidelines. And it's still very iffy with 24 second violations, if you ask me.
I just don't think there's much room for reviews in the NBA without hurting the quality of the product.