The tentative dates for Summer Physics in 2019 are:
Use the Summer Physics 2018 flyer (click here [pdf]) as a general reference for features of Summer Physics.
Is there class/lab/SGL on Memorial Day?
No. Memorial Day is a national and Summer Physics holiday.
Can I take the final a day or two early? I have a wedding/summer camp job/other important thing that conflicts with the last week of the class.
It might be possible to take the final exam on the last Thursday afternoon of class instead of Friday morning. It would not be possible to take it any earlier than that because there would be class/lab/etc that would be missed. The professor advises against taking the final on Thursday afternoon because that will significantly decrease the amount of time for studying and will likely decrease the final exam grade.