If you recall, the previous projection was $20.4 Million, so this isn't a huge difference. I essentially used the holds for all three of the team's outstanding first-rounders (29, LJC and Milutinov), which are a little over $900k each. So you add up the three increases, and you get the differential.
As far as Bertans is concerned, I think he will get something near $3M/3. He's not THAT good of a player in Europe. I don't think he's currently making more than the rookie min right now. Second-rounders don't have rookie scales, so teams can sign them to whatever contracts they want, so the Spurs can give him a three- or four-year deal for however little Bertans will accept over the min, provided they use cap space or the MLE. That first year would probably be guaranteed, as that is pretty customary with contracts structured that way. Similarly, I think they would give Cady a three-year deal starting at the min with perhaps that first year being guaranteed to reward him for going to Austin last season. Bertans' deal would count nearly the same as a first-rounder's, so swapping him out for Milutinov or LJC keeps the cap situation the same, whereas Cady's would have no effect on the cap.
LJC doesn't have a buyout, as he's a pending free agent. This is also why I feel he's extremely likely to come over, as he now has all of the leverage. Milutinov has two more years in Greece, but I am pretty sure his buyouts are affordable.