I think you have it.I still don't understand this "DPL/DAII" thing.
DPL is just another league put together by a few coaches/clubs to generate interest and INCOME.
What does it have to do with US Soccer?
Development Players' (DP) are, it used to be and may have changed, allowed 4 games and once 4 games are played, the club had to either release the player from the squad or make the player Full Time player. The notion is to have a reserve team made up of that would be DP candidates to play onto the DA team. So the league would sync with DA season and allow the clubs without ECNL (since if they have both, they can pull from ECNL team) be available anytime. This probably means no high school or national cup either - just guessing.
In other words, more Kool Aide and the potential to the player to play DA (for parents that didn't quite make DA parents roster).