Ok, after 2 hour hold&chat time I can now confirm what everyone else has been saying- the day is adjusted to correct for the proper arrival/departure and the time has remained the same. My one night reservation arriving 05/30 has a reservation day/time of 05/31 8am- 12noon.
The cast member was lovely and did her best to help with a few logistical questions:
1) What happens if you are in line waiting to buy merch or experience SR when your time expires? No info right now, ask a cast member on site.
2) If your hotel stay has room to add individuals without going over room capacity, when is the deadline to add the names? There is no deadline, but to add a person to a SW:GE reservation you need to 1) call the HOTEL reservation line and add the names to the stay AND 2) call the STAR WARS GE phone line to add the names to your day/time SW:GE reservation. (Please note, I am not personally confident that 1=2, meaning there will be automatic capacity in the SW:GE reservation.)