We should be arriving on Tues June 15. Hopefully around 1 or so. Can we do MGM (just me and DD5yrold) that day/night? She wants to go to MGM because we skipped it the last 2 trips but is going in that late in the day ok for crowds, character sighting etc? Would it make a difference if it was on Wednesday?

I wouldn't worry too much about the crowds beforehand, there is no need to do attractions until the event starts. Just stroll the park and take in any entertainment available. The thing I would consider is the age of you daughter. Most rides during enite are more suitable for older people, and I wonder if a 5 year old can stay up that late without being miserable. You would be better off I think doing the MK for rides at park opening with a child that age. Just some food for thought...