The number of people who can carpool is limited. Everyone I know who does carpool picks up their passengers at bus stops. The buses run nearly empty (partially because it is unlikely they will come within a quarter mile of your destination at either end.)
As far as the toll lane issue, that remains to be seen. If the toll lanes were remarkably faster, people would still have to cross multiple lanes of very slow traffic to exit, backing up the supposedly faster toll lanes. If they are going to make separate overpass exits for the toll lanes 1) there goes any cost advantage and 2) they aren't building them now.
It seems likely they will have to wall off the toll lanes to prevent people from simply going around the toll booths, and they probably won't provide exits except at key points, greatly limiting their usefulness.
The tollway will be walled off, and the "tollbooths" will be entirely electronic (EZ Tag).
According to the schematics it looks like there will be one exit to the mainlanes for every three freeway exits.