Although, it's saying 5:30am start times for the races. So maybe we won't be forced to watch all these people run through the parks during normal hours? This is really going to be a bummer if the parks are flooded with spectators just standing there like a 4 hour parade.
The Expo, where the runners get their race bibs and get race gear, is at ESPNWWOS, so that's way out of the way of all the parks.
The 5k race on Thursday starts at 6:00 am, and runs around and through Epcot. It should be done by 7:00 am, at the latest. Epcot is scheduled to open at 9 for WS and 11 for FW
The 10k race is on Friday and starts at 5:30, and also runs around Epcot. It runs a little more around the area, including the Epcot resorts. It should also be done by 7:00 am. Like Thursday, WS opens at 9, FW a 11.
The 1/2 marathon also starts at 5:30 in the morning, and starts at Epcot, runs through MK, and then runs back to Epcot, into FW for a little and then out the Epcot parking lot. It should end by like 9:30-10. MK will be closed when the runners run through it, and all the runners should be gone by the time it opens at 9 am. Epcot is also following the 9 and 11 strategy. There might be a few of the slowest runners running into Epcot while the park is open, but it's not many.
The Full marathon starts at, unsurprisingly, 5:30 am on Sunday the 7th. It runs from The Epcot parking lot to MK down to AK due east to ESPNWWOS, through HS and then through IG into Epcot, and out the FW exit to the parking lot. As for dealing with runners, MK, again, everyone will be long past MK before it opens. AK, you might get the last of the runners going through before park open, but the vast majority will be gone. HS, the last of the runners should be out by noon. Epcot, they are out by 1:00 pm. Even so, most of the runners should be gone well before those times.
Most of the spectators are going to be on the roads and at the Epcot parking lot. The only place with organized crowds in the parks is in MK, and they'll be gone by 8:30, and the park opens at 9.
The biggest thing you have to worry about is everyone clanging as they walk around with multiple medals around their neck.