Re: parade times
Well, Joe Carioca can flap his wings, fly above the crowds, and catch all four parades, but we flightless mammals will have a tough time if the plan is to perch at the MK parade's starting point at the back of the park, actually stay around to watch each parade to the end, then exit the park through the crowds that are still sitting curb-side for the parade to reach their vantage point, travel to the next park....
I'd say three out of four is very easy, but all four would be a task worthy of Buzz Lightyear.
Slam-dunk plan (3 out of 4):
1) Share a Dream Come True Parade (MK - 3:00pm) - view from parade start in Frontierland, hightail it through Adventureland, dodge the Main St. crowd by walking through the shops. Dash to TTC for car or bus to Studios.
2) Stars and Motor Cars (Studios - 4:00pm or 5:00pm depending on season) - view from end of parade route if parade starts at 4:00pm (usually Hollywood Blvd.), or anywhere you please if it runs at 5:00pm.
3) Tapestry of Dreams (Epcot - do the 8:10pm parade and eat dinner at a reasonable hour). Take boat/walk from Studios to World Showcase.
If you wanted to Buzz around, figure you have 40 minutes to get from MK to AK following the end of the MK parade in Frontierland (possible, not probable, as you'd be all the way back in Frontierland), and it'll take time to get to Harambe at AK from the front of that park, too. Catch AK parade from Harambe village (stand on the bridge) at its start at 4:00pm. By 4:15pm you may be on your way out of the park. If the Studios parade starts at 4:00pm, maybe you can get there to see the tail-end of the parade. If it starts at 5:00pm, you'll probably be cool. Again, for Epcot, you can catch the 8:10pm parade, no sweat.
Maybe there should be a merit badge for this event?