I would read it like this:
1. Ender Quartet
2. First Meetings & EiE
3. Shadow Series

I do believe that is correct, but there is one contradiction to that theory in Children of the Mind . I can't find the specific quote and page, but it's in the chapter where Val and Miro visit the Hive Queen and Val says something like, "You damn well care about dying". I happened to read...

I just finished reading Speaker again, and there is a major difference between the Park Shift and the egg. The egg is used to gradually bring the ship up to near-light speed, the keyword being gradual. The Park Shift uses the Park Instantaniety (sp?) Principle to function, which as the name suggests...

I think the "right" answer is a bit deeper than just the distance between the Queens and the drones. The surviving queen made it clear the Ender that they accepted the humans as intelligent, and didn't want to fight them anymore; that was why they didn't try to invade Earth again. But it's...

Does this Park Shift have anything to do with the egg? And if so why couldn't OSC explain both at once?

We only hear about the park shift in Speaker, so it probably wasn't called that yet.
It's a bit hard to explain something that (effectively) doesn't exist at that point.