From what I understand, Main Street is open an hour earlier before the rest of the park... Not sure if this has changed but at least this is what Ive heard from others and have experienced the last few times ive been to DL.
Not exactly. It varies from day to day. MM means Magic Morning, which is the new name for the old Early Entry system.
On days where the park opens at 8AM (non MM day), everything opens at 8AM. Main Street does not open early.
On days where the park opens at 8AM (MM day), MM guests are allowed in at 7AM for open attractions, while non MM guests have to wait until AT LEAST 7:30AM until they are allowed into the park. The time that non MM guests enter depends on the crowd size.
On days where the park opens at 10AM (non MM day), Main Street opens at the earliest 9:30AM, with the rides opening at 10AM.
On days where the park opens at 10AM (MM day), MM guests are allowed in at 9AM for open attractions, while non MM guests have to wait until AT LEAST 9:30AM. The time that non MM guests enter depends on the crowd size.
On days where the park opens at 9AM (both MM days and non MM days) I have heard of a variety of different opening procedures.
Basically the bottom line is that if the crowds outside the gates grow enough to warrant it, then they will probably allow guests in to Main Street before official park opening.