Actually they are adding an extra lane each way between exits for merging and accel/decel, and 2 toll lanes each way for all cars. Doesn't make sense to say that going from 6 to 10-12 lanes(which as configured would double capacity) won't impact congestion. You'll have a choice, pay to use the fast toll lanes(where the rates will vary based on demand to keep traffic moving at 55+mph) or the busier free lanes.
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.