There's been no word as of yet as to whether other teams aside from the ones already listed will be unlockable. Charles Barkley has always been difficult to sign on to a basketball game so I feel that Suns squad could be iffy, even if there did end up being more teams available.
The '95 Knicks are being used rather than the '94 squad because the classic teams included were all opponents during the 10 "Jordan Moments" being used for the Jordan Challenge. The '95 Knicks were the opponents for Jordan's 55 point game shortly after his comeback.
Finally, no word on Marv Albert and I hate to speculate - as I know nothing - but I wouldn't hold your breath. 2K mentioned era-specific commentary but as has been mentioned in other threads, I've gotten the impression this would be more of Kevin Harlan mentioning Michael Jordan and his exploits rather than having an entirely different broadcasting team.