Information regarding Grad Night.
can be found by reading the Chaperone guide from Disney, available here.
There is also additional information on the Grad Night event at the Disneyland grad night site
Disneyland Grad Nite | Celebrations & Field Trips at Disneyland Resort
In a nutshell-
"Gradnight" tickets cost $69 dollars. Ticket allows Park Hopping starting at Disneyland/California adventure opening. It appears that park hopping will no longer be available to grads once the "Grad night" party begins.
The actual "GradNight" portion of the event is as follows:
Info taken from 2013 Gradnight chaperone handbook.All Grads must be inside Disney California Adventure by one hour after park close. At that time, the gates will be locked and no Grads will be allowed in or out without Chaperone consent. Any Grad trying to come inside Disney California Adventure Park one hour after park close will need a Chaperone to vouch for them. Grads can reach out to Cast Members at the Guest Service Building in the Esplanade to assist them in reaching a Chaperone. Any Grads inside Disneyland Park at the start of Grad Nite will be asked to head over to Disney California Adventure